Entomology Publications Entomology

2005 Insect / Receptors Thomas W. Sappington U.S. Department of Agriculture, [email protected]

Alexander S. Raikhel University of California, Riverside

Follow this and additional works at: https://lib.dr.iastate.edu/ent_pubs Part of the Entomology Commons, and the Population Biology Commons The ompc lete bibliographic information for this item can be found at https://lib.dr.iastate.edu/ ent_pubs/483. For information on how to cite this item, please visit http://lib.dr.iastate.edu/ howtocite.html.

This Book Chapter is brought to you for free and open access by the Entomology at Iowa State University Digital Repository. It has been accepted for inclusion in Entomology Publications by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Insect Vitellogenin/Yolk Protein Receptors

Abstract The protein constituents of insect yolk are generally, if not always, synthesized outside the oocyte, often in the fat body and sometimes in the foilicular epithelium (reviewed in Telfer, 2002). These yolk protein precursors (YPP's) are internalized by the oocyte through receptor-mediated endocytosis (Roth et al., 1976; Telfer et al., 1982; Raikhel and Dhaclialla, 1992; Sappington and Rajkhel, 1995; Snigirevskaya et al., I 997a,b). A number of have been identified as constituents of insect yolk (reviewed in Telfer, 2002), and some of their receptors have been identified. The at xonomically most wide pread class of major YPP in insects and other oviparous animals is vitellogenin (Vg). Although several insect Vg receptors (VgR) have been characterized biochemically, as of this writing there are only two insects from which VgR sequences have been reported, including the yellowfevcr (A edes aegypt1) (Sappington et al., 1996; Cho and Raikhel, 2001 ), and the cockroach (Periplaneta americana) (Acc. no. BAC02725). A BLAST search of the recently published genome sequence of the malaria mosquito (Anopheles gambiae) (Holt et al., 2002) yielded a predicted amino acid sequence (Acc. no. EAA06264) with 54% identity to the A. aegypti VgR sequence, and will be referred to here as the A. gambiae VgR.

Disciplines Ecology and Evolutionary Biology | Entomology | Population Biology

Comments This is a chapter from Sappington, T. W. and A. S. Raikhel. 2005. Insect Vitellogenin/Yolk Protein Receptors. In: A. S. Raikhel (ed.), Reproductive Biology of Invertebrates, Vol. 12, Part B: Progress in , Science Publishers, Inc., Enfield, USA/Plymouth, UK, pp. 229-263.

Rights Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The onc tent of this document is not copyrighted.

This book chapter is available at Iowa State University Digital Repository: https://lib.dr.iastate.edu/ent_pubs/483 8. INSE T VITELLOGE IN/YOLK PROTEIN RECEPTORS

2 TH0\1AS w. SAPP! GTO I AND ALEXA DER s. RAIKHEL 'USDA-ARS, CICGRU. Genetics Laboratory, Iowa State University. Ames, IA 50011. USA. 1Department of Entomology, Unhlersity of California, Riverside, CA 92521, USA.

I. I T RODUCTIO

The protein con tituents of insect yolk arc generally, if not always, synthesized outside the oocyte, often in the fat body and sometimes in the foilicular epithelium (reviewed in Telfer, 2002). These yolk protein precursors (YPP's) are interna lized by the oocyte through receptor-mediated endocytosis (Roth et al., 1976; Telfer et al., 1982; Raikhel and Dhaclialla, J 992; Sappington and Rajkhel, 1995; Snigirevskaya et al., I 997a,b). A number of proteins have been identified as constituents of insect yolk (reviewed in Telfer, 2002), and some of their receptors have been identified. The taxonomically most wide pread class of major YPP in insects and other oviparous animals is vitellogenin (Vg). Although several insect Vg receptors (VgR) have been characterized biochemically, as of this writing there are only two insects from which VgR sequences have been reported, including the yellowfevcr mosquito (A edes aegypt1) (Sappington et al., 1996; Cho and Raik.hel, 200 1) , and the cockroach (Periplaneta americana) (Acc. no. BAC02725). A BLAST search of the recently published genome sequence of the malaria mo quito (Anopheles gambiae) (Holt et al., 2002) yielded a predicted amjno acid sequence (Acc. no. EAA06264) with 54% identity to the A. aegypti VgR equence, and will be referred to here as the A. gambiae VgR. In cyclorraphan (higher) Diplcra such as Drosophila, the major ypp belongs to ~ n evolutionarily different class of proteins than Vg, and was originally des1gn~ t ed "yo l~ polypeptide" or VP (Bownes, 1992; Bownes and Pathirana, 2002). There 1s no evidence for Vg production or Vg in the e flies (Bowne and : athirana, 2002). The putative receptor for the YP' in D. melanogaster was 1dcnt1fied and cloned by taking advantage of the volkless mutation (Schonbaum et 230 REPRODUCTIVE BIOLOGY OF INVERTEBRJ S al.. 1995. 2000; Bownes and Pathirana, 2002), and is n.' red to as the yolkless protein (YI). Despite their unrelated ligands, YI and ct VgR's share high sequence identity (Sappington et al., 1996), and polyclon ntibodies raised to A. aegypti VgR recognize the D. melanogaster YI (Richard l al., 2001). Lipophorin (Lp) serves as a shuttle between the fat body and the developing oocyte, and in ome insects, such as lepidoptcrans and mosquito, is itself sequestered in the yolk (Kawooya and Law, 1988; Sun et a 2000; Telfer, 2002). The Lp receptor (LpR) has been cloned and sequenced from both the locust (loc11.Sta migratoria) (Dantuma et al., 1999) and mosquito (Cheon et al . 2001 ). The locust LpR is expressed primarily in the fat body, but it is also present in the ovary. Thus, Lp may be cndocytosed by L. migratoria oocytes, but if so it is probably only in small amounts, because there is no evidence that Lp ·~ removed from the haemolymph during vitellogenesis (Gellison and Emmerich, 1978). Two proenzymes, vitellogenic carboxypeptida e (VCP) and vi tellogenic cathepsin B (VCB), are internalized by A. aegypti oocytes and deposited in the yolk bodies (Hays and Raikhel, 1990; Cho et·al., 1991, 1999; Snigirevskaya et al., 1997a). It was recently determined that VCB and VCP bind to Lp, and are thus carried into the oocyte when Lp binds to the ovarian LpR (Raikhel, unpublished). Anti-Aedes VgR polyclonal antibodies recognized an abundant 80-kDa protein in D. melanogaster ovaries in addition to the YI (Richard et al., 2001 ), which possibly represents an ovarian LpR. Putative LpR's have been identified in the Drosophila genome (Culi and Mann, 2003). There arc a number of other protein components of yolk that have been reported from insects, but little is known about their receptors. A 30-kDa protein called microvitellogcnin is internalized along the same pathway as Vg in Manduca sexta (van Antwerpen et al., 1993), but does not compete with Vg fo r receptor binding sites in this insect (Osir and Law, 1986) or in Hya/ophora cecropia (Kulakosky and Telfer, 1987). ln M. sexta, a blue biliprotein called insecticyanin is internalized by receptor-mediated endocyto is, and it does not compete with binding sites for Vg or Lp (Kang et al., 1995). Lack of competition among ligands sugge ts that they either have separate receptors or non-overlapping binding sites on the same receptors.

A. LDLR-Superfamlly Receptors

Significantly, the insect VgR 's, YI, and LpR's are all members of the low-density receptor (LDLR) superfamily, named after the LDLR first described from ~u~a~s (Yamamoto et al. . 1984). The LDULDLR system is critically involved in hp1d and homeostasis in mammals (Brown and Goldstein, 1986; Willnow, 1999). VgR's belong to the same upcrfamily (Bujo et al., 1994; Okabaya hi et al., 1996), and are al o known as very low-den ity fipoprotein receptors (VLOLR'~) . Though mammals do not produce eggs with yolk, a number of LDLR-supcrfam1ly members mediate uptake of and by cells INSECT \'ITELl.O\ I YOLK PROTl.I. RECEPTORS 231 of the. yolk-sac (~erz and f C:: 1999; W1llnow. 1999) Venebrate opoB-100 the pnmary protein. compon1. t c LDL and the ligand for LDLR • 1 dcnv ed firom ' an ancestor of m ect and n m1tode Vg's (Chen et al 1997· . ·· • s appmgton and Ra1kh~I . 1998b;. Sappington ti al 2002). Like the venebrate LDL. the nematode Vg 1s involved m chole terol transport, and thus the Vg/VgR sy tern 1s clearly an evolutionary precursor to the LDL LDLR system m vertebrate ( chneidcr, 1996: Matyash et al .. 200 I). Although LDLR- upcrfamily protem tradiltonally have been \ 1ewed as stnctly endocytotic m function. recently they ha\e been implicated m signal transduction, a role that may be widespread among the e receptors (Herz et al., 2000; Gotthardt et al., 2000; Stockinger et al., 2000; Barnes el al., 200 I; Li et al.,200 Ia, b, c; Herz and Strickland, 200 I; Nykjaer and Willnow, 2002; Strickland, et al., 2002). LDLR-superfamily members include a variety of proteins, all of which are characterized by various arrangements of the same five structural components (Fig. I): I) Class A complement-type imperfect repeats, often referred to as ligand­ bmding repeats. These contain six cysteine residues which fonn an invariant pattern of disulfide bonds (Bieri et al., I 995a,b ). 2) Class B epidermal growth factor (EGF)­ type imperfect repeats. These also contain six cysteine residues, but the latter fonn a different pattern of disulfide bonding than the cysteines in Class A repeats (Campbell and Bork, 1993). 3) Y1¥XD imperfect repeats, that invariably occur in groups of six which fold to form a compact 6-bladed b-propcller structure (Springer, 1998; Jeon et al., 2001 ). This domain is often considered part of a lar~er EGF precursor homology domain, which includes the Class B repeats (e.g., N1mpf a~d Schneider, 1998; Hussain et al., 1999). 4) A single-pass transmembrane dom_am near the C-terminus. 5) A cytoplasmic tail that includes one or mo~e tyrosme­ based or dileucine-based internalization signals. ln addition, there ts often an extracellular 0-linked sugar region proximal to the membrane, a~d in s.o'.11e cases the presence or absence of this domain is determined by differential sphcmg (e.g., Bujo et al.. 1995). Besides the presence of these domains, Hussain et al., ( 1999) lists other characteristics of LDLR-superfamily members, including cell-surface expression, a requirement of Ca+ ~ for ligand binding, and internalization of ligands by receptor-mediated endocytosis. LDLR-superfamily members, including vertebrate VgR 's, often bind multiple unrelated ligands (Mac Lachlan et al. . 1994; Gliemann, 1998; Hussain et al., 1999; Mahon et al., 1999; Strickland et al.. 2002). It was recently demonstrated that the YP2' of the pyralid moths Plodia interpunctello and Galleria me/lone/la, and the egg-specific protein (ESP) of the silk moth Bombyx mori, are homologous to the YP's of higher Diptera (Sappmgton. 2002). ESPNP2's are minor constituents of the yolk in these insects, while Vg ts the maJOr component. Given the similarity of the Drosophila YI to the mosquito VgR (Sappington et al., 1996), and that lepidopteran oocytes internalize both YP2/ESP's and Vg (Shirk and Perera, 1998), it seems likely that a single VgR/YI protein recognizes both ligands. Recently, Bownes et al.. (2002) demonstrated that D melonogaster YP I expressed in bacteria 232 REPRODUCTIVE BIOLOGY OF INVERTEBRATES is internalized by A. gambaie oocytes. In contrast, the mosquito VgR and ovarian LpR are different proteins (Sappington et al., 1996, Cheon et al., 2001). The VgR has not been sequenced from l. migratoria, but 1t · ize on SOS gels (180 kDa) (Hafer and Ferenz, 1991) is more similar to that of the mosquito VgR (205 kOa) (Dbadialla el al., 1992; Sappington el al., 1995) than to that of the mailer locu t LpR, judging from the deduced amino acid sequence of the latter (Da~tu~a ~I al. 1999). Competition experiments with cultured Manduca sexta ovaries Uldicated that Vg and Lp are internalized by two different receptors as well (Osir and La\\. 1986; Kawooya el al., 1988). However, in Hyalophora cecropia, evidence suggests that only a si ngle receptor is involved in endocytosis of these two ligands (Kulakosky and Tel fe r, 1990).

B. Receptor Modularity and Evolution

Insect VgR/Yl's and LpR's, like all LDLR-supcrfamily members, are modular proteins. Modules are fundamental building blocks of protein structure and function (Bork et al., 1996; Henikoff el al., 1997), and modular rearrangements, recruitment. duplications, and deletions are common modes of diver ification during evolution (Doolittle, 1995; Schmid and Tautz, 1997; Schuler, 1998; Springer, 1998). The evolutionary mobility, or modularity, of any equcnce motif i demonstrated either by its presence as independent units in unrelated protein , or by different internal locations among homologous proteins (Doolittle, 1995; Bork er al., 1996). The Class A repeats, Class B repeats, and YWXD ~-propeller region in LDLR­ superfamily proteins are clearly modular by both crttena, appearing independently in a diverse array of other unrelated composite proteins (Campbell and Bork, 1993; Suzuki and Riggs, 1993; Springer 1998), and occurring in different numbers and arrangements among different families withm the LDLR upcrfamily (Fig. I). Class B EGF repeat domains are very widespread (Bork er al . 1996), occurring, for example, in about I% of all human protcms (I lenikoff et ul. 1997). Both YWXD and Class A domain arc among the most common module~ that have been huffied among various animal extracellular protem (Doolittle, 1995, Bork ct al , 1996; Fass er al., 1997; Altschuler al. 1997). lntron boundaric can be useful in demarcating module in the extracellular poruon of a protein (Bork and Gib n, 1996), and m the case of vertebrate LDLR • and VLDLR' • the e'on com: pond to functtonally defined module (Brown and Gold tetn, 1986, 1mpr and chnc1der. 199 ). Likewi e, four of the fhc intron-cxon boundane of the 4 CJt'g}pt1 VgR gene correspond to domain boundarie (Cho and Raakhel, 200 I ). Modular con truction complicate elucidation of c\lolutionary hi tone and relationship Among LDLR- upcrfamily members, ~htch 10 tum complicat protein eta ificat1on, becau c the ha tory of a mosaic protein cian be confounded by Lhc independent ht tone or it component module . rht i • problem for modular protein 1n general, for "htch there 1 no con en u on h(lw lo clo.,,afy them SECT VITELLOGENINIYOLK PROTEIN RECEPTORS 233 (Doolittle, 1995). Two recently characterized t . . repeats, and on this basis were designated LDLRprol ems cont~tn Class A binding al., 1998) and LRP4 (Tomita et al 1998) H -re ated protein-3 (LRP3) (I hti et ·• · owever they do t h oth er modules that define classic LDLR-type r ' no s are any of the Herz and Bock 2002) and s h d . . eceptors (Howell and Herz, 200 I· • • uc es1gnattons add to th fu . . . • Because single LDLR-superfamily rece t ft e .con s1on m classification. P ors o en can btnd many 1· ds t'i • to a receptor based on one of the ligands it binds is not alwa s sa~~~c~ re em~g et al. . ( 1995) and Nimpf and Schneider ( 1998) recommende/calling LDLryR. , BuJod vertebrate VgR • ( VLDLR' ) , s an S or s LR7 s and LR8 's, respectively based on the ~mber of Class A modules these receptors contain. In this system: the A. aegypti . gR and D. melanogaster YI are LR13's (Sappington and Raikhel J998a) d insect. L PR' s .are LR8 ' s. However, this system of nomenclature is' not entirely• an s~tisfac tory either, because phylogenetically closely related receptors can have d1ffere ~~ numbe~ of repeats (Brandes et al., 1997; Sappington and Raikhel, J 998a). In add1t1on, varying numbers of Class A repeats can occur within proteins coded by the ame gene via differential splicing (Kim et al., 1997; Brandes et al., 1997, 200 I; Stockinger et al., 1998; Clatworthy et al., 1999; Korschineck et al., 200 J) . With these limitations in mind, and in the context of this review in which the YPP­ binding function of the receptors is of primary interest, we will refer to the receptors by relevant functional names. One of the most striking structural characteristics noticed when comparing LDLR-superfamily members is the clustering of Class A modules into 1-4 distinct ligand-binding domains, with a characteristic number of modules per domain (Fig. 1). Complete VgR sequences are known from four species of (Bujo et al., 1994; Okabayashi et al., 1996; Davail et al., 1998; Li et al., 2003), and arc characterized by a single ligand-binding domain containing eight Class A modules. Similarly, the mosquito ovarian LpR has eight Class A modules in a single cluster (Cheon et al., 2001 ). Insect VgR/Yl's have two clusters of Class A modules, the first of which contains five modules (Fig. 1-2), and the second containing either eight (A aegypti VgR, D. melanogaster YI) or seven (P. americana and A. gamb1ae VgR's). Altgnment of the modules (Fig. 2) indicates clearly that the fifth Class A module m Cluster II of A aegypti and D. melanogaster VgR/YI ' i not pre ent in the putall\.e VgR cquence of P. americana and A. gombiae. In addition, the first Clas A module in P americana appears to be truncated (Fig. 2), and 1t i unclear whether th1 repre ents a splice variant or the actual ab ence of the module in the gene. The nematode (Caenorhabditis elegans) VgR (named RME-2) contains a 1oglc domain of five Clas A modules (Grant and Hirsh, 1999) Although reminiscent of the five-module cluster found in insect V gR/Y\'s, preliminary fingcrpnnt analy 1 (Sappington and Raikhel, 1998a) suggests the domains arc not cJ1rcctly homologou (TWS unpublished data). LRPI 's and LRP2's (mega Im. ) ore \Cf)' lariie receptor.. which conuun four clusters of 2-7, 8, 10, and 11 -12 module (fig. 1). Ch1d.cn Vg 1. a ligand for both the single-cluster chicken VgR nd the ·module chmcr in the chicken LRP I (Nlmpf et al., 1994). Cell Membrane If C I s-¥ ------C II aB-~······------·-·---~ l8S C III C rv GgLRP

• Cius A (Ligand Binding) Repeat • Cius B (EGF) Repeat

• YWXD &.Propeller

~ 041nked Carbohydrate Domain

T~neHellx ""\/ Cytop¨c Tall AaVgR N--~ - ••••••- ~--;----- C II

DmY/ N --~--C~-~ • - ••••••-C II - •

CeVgR LL

1 Fig • Rttcpiors from lhc LDLR upcrfamtly known to cndocytose yolk protein precursors into oocytes. emphasizing IUTllflgcmen1 or modular domains. C-rmnmus or each receptor ts located on the cytopla mic side of the cell membrane, and the N-tcrm1nus is extracellular. C I. first clu.,1cr of Class A (hgand-bmdmg) repeat m multi-cluster receptors; C II, second cluster, etc. Relative locations of tyrosine-based (NPXY) or d1 lcuc111c· bnqcd (LL or LI) mremaJ1za11on tgnal rn the cytoplasmic 1ail arc indicated GglRP chrckcn (Gu/Im gal/11s) LDLR-n:latcd protein; GgVgR, chicken (G gull11 » vucllogchn/111 ' . 11 pl lf /)m't'/ lnuc tly ( 1>rn.1or 'ti aegypli) luVgR. receptor; AulPR,mtlanotrutcr) mosqu110 yo (Aedeslkl protein (orlipoph VP t"eeq>lllr);orin receptor; c .. vgR, ncmalndmosqu110 ... I(" 'IHlr~··hc.l•lt (A·1o:":"~K.':·p~1~1):":::'c:o "'' wu) ~g"le~c :n':t~ o:·:~:~:~n:..:~«:·:.,r:•:"~'~'':".:'t~M~l= ll~...,.--!!!!!!!l!!!!!!-!!!!!!!i!!!~!l!?E!!r INSECT VITEU 0<1ENIN/YOLK PROTEIN RECEPTORS 235

A search of the D. melanogaster genome (Adams et al., 2000) revealed the presence of seven LDLR superfamily members (Cuti and Mann, 2003), including homologue to the very large LRP2's of vertebrates (Herz and Bock, 2002). However, the role of these large receptors in insects is unknown. It has been hypothesized that the smaller members ~f the LD LR-superfamily evolved from the truncation of larger receptor genes (W1llnow, 1999), but phylogenetic analyses of individual c lusters suggests that the ancestral LDLR-type receptor contained a single cluster of at lea t seven Class A modules (Sappington and Raikhel, J 998a).

II. CLASS A LIGAND-BI NDING DOMAINS

A. Module Structure

Comparisons of Class A module primary structure among a wide range of LDLR­ superfamily members reveals a number of highly conserved residues (Ullman et al., 1995; Sappington and Raikhel, I 998b), including Class A repeats in insect VgR/ Yl 's and LpR's (Fig. 2-3). Structures for several C las A repeats from mammalian LDLR and LRPl, have been solved by X-ray crystallography or NMR spectroscopy (Daly et al., I 995a,b; Fass et al., 1997; Huang et al., 1999; Dolmer et al., 2000; North and Blacklow, 2000; Simonovic et al., 2001 ), as has the module from the unrelated avian leukosis and sarcoma virus receptor, T va (Tonelli et al., 200 I). These structures have made clear that most of the conserved residues are involved in maintaining global structure. The tertiary structure of each of these modules is very similar (Fig. 3), and is determined and stabili zed by three disulfide bonds among the six cysteincs ( 1-3, 2-5, and 4-6 pattern), a small hydrophobic core, and the coordination of a ca• ion by several negatively charged residues. Class A modul es consist of two loops, each created by a disulfide bond (Fig. 3) (Daly et al., I 995a,b; Fa s et al , 1997; Huang et al., 1999; Dolmer et al., 2000; North and Blacklow. 2000). A short ex-helix links these N-terminal and C­ tenninal loop (Huang et al. 1999), while their apexes are connected by a third disulfide bond. The importance of correct disulfide bond formation to function is highlighted by the large proportion ( I 3) of defective mutant LDLR's in humans that are caused by the lo~ of a con:.en:ed C tn a Class A module (Morash et al., 1998). The con cncd r and I re iduc~ m the -terminal loop appear to share hydrogen bond. (lluan • tt ul, 1999). and together eompo e the hydrophobic core of the module (OJI) ti al, 199Sa,b. Oolmcr et of 2000). Replacement of the I with a hydrophilic D n: 1Juc cu lo 'of function (c er t•t al, 1988; Rus ell et al., 1989). Correct d1,ulfidc honJm and m•11ntcn.1ncc of -terminal loop topology in Class A module r~>tjutrc the bmhrkasten and Ferenz, 1985; Kt>nig et al., 1987; Warrier and Subramoniam, 2002), or mutations of the negatively charged residues coordinating ca++ binding in Class A modules in the case of human LDLR (e.g., van Oriel et al., 1987; Esser et al., 1988; Rus ell et al., 1989), can abolish ligand binding, indicating the importance of Ca· in maintaining correct module and domain structure. Post-translational modification of Class A modules has not been studied to a great extent. There are a number of potential N-linked glycosylation sites in the Class A domains of m ect VgR/Yl's and LpR's (Sappington et al., 1996; Cheon et al., 2001). Hafer and Ferenz (1991) presented evidence of heavy glycosylation of the locust VgR, but the specific sites have not been identified. Hom et al., (1997) foun~ ~at recombinant fragments of LRP I expressed in hamster kidney cells and cons 1 stt~g of 2-3 Class A modules were glycosylated. Lack of ligand binding by rccomb~nant Class A domains expressed in bacteria (e.g., Ru nova et al.. 1997) may be du~ ID part to lack of glycosylation by a prokaryotic system. On the other hand, bactenalty-exprcs cd LRP fragments containing 3 Class A modules successfully bound thr.ce different ligands (Vash et al., 1998), indicating that post-translational mod1ficat1on wru. not necessary for binding in those ca cs.

B. Domain tructure

Although there arc a few example~ of a 1Dgle Clas\ A module binding a ligand, c pccially opponuni'ltic ligands like' iruses (Zmglcr ct al. , 1995; Rong et al., 1998), evidence suggc:.ts that multiple module., arc m\'ohed m mo 1 LDLR-superfamily receptor ligand m1eroct1ons (Mocstrup, 1994; Gliemann, 1998; llcrz and Strickland, 2001 ). All known LDLR- uperfomtly rcccptOI"\ in,ohed ID yolk protein precursor intemah1a11on conwtn clu .. 1cr., of multiple Cl A modules Module within these c lu s t c ~ arc connected by .. linker." bct\\ecn the la I C m one module and the first c in the next (I 1g. 2). MR !ltudics of conuguou Cla A module linked by four ammo ac id rc-.iduc indicate that the moJul arc tructurally mdcpcndcnt of one INSFCT vm ()( ENI!\ YOLK PROTH RE Cf PTO RS 237 Linker Length VgR/Yl Clu•t•r I PaVgRl C · PSGF...... HNGE .... CIN. DDKHCDGTSDCKOOSDE. FD. C 4 AaVgRl C.AENE .... . Y ~ . . DNGA .... CIP.DVNHCNGAKDCTDGSDE.VG.C 4 AgVgRl C.GAHE .... . FQC .. ENGA .. .. CIP.AAGHCNDIQDCADGSDE.SG.C 4 DmYPRl C.DAGQ ... .. FQC .. ROGG ... . CIL.QAKMCDGRGDCKDSSDE.LD.C 4

PaVgR2 C.KEPH .... WFRC .. HNGR .... CTS.KSFHCDGVDDCGGWSDE.ED.C 9 AaVgR2 C.KKPM .. .. WYRCK. HDKS .... CIS.ATFLCDKHDDCPLGDDE.EN.C 11 AgVgR2 C.RAPF . .. . WYRCR. HEST .... CIS.GSSRCDGQRDCLGGDDE.EN.C 11 DmYPR2 C.RPPH .. .. WFPCAQPHGA .... CLA.AELMCNGIDNCPGGEDE.LN.C 17

PaVgRJ C.TADE .. ... WRC .. VDNN .... CIF.MDWVCDGKQDCMDGSDELQG.C 5 AaVgR3 C.SKFE ... .. FTC .. TDKM .... CIP.LDLVCDGVS.CLDGSDETIG.C 6 AgVgR3 C. SKAE . .... FTC .. TORA . ... CIP.ADLVCDGVQHCLDGSDETIG.C 6 DmYPR3 C.SKYE .. ... FMC.QQDRT .... CIP.IDFMCDGRPDCTDKSDEVAG.C 6

PaVgR4 C . .. EOG .... FVC .. GNYH .... CIP.NSFLCDGFDDCGDNSDE.KL.C 10 AaVgR4 C .... KG .... FVC .. KNKR .... CINSHDWVCDGIDDCGDGSDE.EN.C 3 AgVgR4 C .... KG .... FLC .. RNKH .... CLQSHHWVCDGLDDCGDGSDE.EH . C 3 DmYPR4 CPGEGH ...... LC .. ANGR .. . . CLRRKQWVCDGVDDCGDGSDE.RG.C 3

PaVgRS C.KLEKN . . . LFLCA.DRQE .... CVE.VRELCDGTPHCYDGSDEGPA.C 6 AaVgRS C.DLEHG ... KFECA.DNST .... CVD.LK.LVCDGKDDCGDHSDEGGS.C 4 AgVgRS C.TLEHG ... KYECA.NNHT .... CVD.VTQVCNGADDCGDGSDEGPG.C 6 DmYPRS C.EPQKG ... KFLCR.NRET .... CLT . LSEVCDGHSDCSDGSDETDL.C 5

.YgR/Yl Cluster II PaVgRl ...... CRDGSDE. YY. C 4 AaVgRl C.E ...... FKC .. TSGE .... CLT.ISKRCNGNKDCADGSDE.KG.C 10 AgVgRl C.A ...... FRC . . ASGE .... CLA.RGLRCNGRVDCMDQSDE.QG.C 12 DmYPRl C.E ...... FRC .. HSGE .... CLT.MNHRCNGRRDCVDNSDE.MN.C 11

PaVgR2 CNEDLQ ..... FKC .. RTGO .... CIV.KSWYCDGSKDCEDGSDE.EN.C 4 AaVgR2 C.QYDE .. .. . FMCA.DKSK . ... CID.QTRRCDEHVDCGDGSDE.MK.C 8 AgVgR2 C.RWNE .... . FRCA.DGSR .... CIA.ATSRCDSRPDCADRSDE.AN.C 8 DmYPR2 C.SPSQ .... . FAC . . HSGEQ ... CVD.KERRCDNRKDCHDHSDE.QH.C 8

PaVgR3 C.EPSA ..... FKC . . ALGQ .. . . CIP.EEWVCDGQSDCVDDTDE.QN.C 4 AaVgR3 CHEHQHA ...... C .. PDGM .. .. CID.VNTLCDGFPDCLDGSDE.VG.C 12 AgVgR3 CTRYQFS ...... C . . ADGF .... CVD.ATARCDQVPDCPDGSDE.QE.C 13 DmYPR3 CHVHQHG ...... C .. ONGK .... CVD.SSLVCDGTNDCGDNSDE.LL.C 5

PaVgR4 C GPGA ...• . FSC .. GNGR .... CID.QTLLCNNVDDCGDRSDE.DP.C lS .AaVgR4 C.GPLM ....• FRC .. NMGQ .... CIP.KWWECDGNPDCTDGSDEHDK.C S .AgVgR4 C.AAGM ..... FRC .. NSGH ...... · · .ALVCDGNDDCGDGTDE.EH.C lO c:EPGM ..... FQC .. GSGS . ... CIA.GSWECDGRIDCSDGSDEHDK.C DmYPR4 4 ...... PaVgR c" :oAGF:::::TKC .. ALGH •... CIE.DRLLCDGNNDCGONSDE:i.N:c AaVgRS ...... 6 AgVgR 238 RI·PROD CTIVE BIOLOGY 01 I' TE BRATES

DmYPRS C.PPDM ..... HRC •. LSGQ .... CLO. L CDGHNDCGDKSDE.LN.C lO

PaVgRS C.KEGE ..... YTC . HPHGKNVTICLP.SSG GTAECPLGDDE.RG.C 1 AaVgR6 CVGLEOONPTKYLC.PRSGK .... CLD.IAVRCNGTAECPDGEDE.AG.C 2 AgVgRS CSEQAIANGTAYRC.ARSGA . ... CLP.AAARCNGTAECPHGEDE.TG.C 2 DmYPR6 C. AEOQ .•... YQC. TSNLK ... I CLP. SAVRC?lGTTECPRGEDE ·AD· C 3

PaVgR6 C.QDFQ ..... FTC .. YNGK .... CIP.SEWVCDG INDCGDGSDENNARC ll AaVgR7 C.GLQE ..... FQC .. KSGK .... CIR.KEWRCDKEVDCODGSDE.VD.C ~! AgVgR6 DmYPR7 ~:~~:::: :~~~: :;~:: :~~::~::~~~~~~~~~:~:~ 21 3 PaVgR7 C.TD ...... YAC .. NDGQ ... . CIS.LSLACNNKRNCEDGSDEGGQ.C AaVgR8 C.GEGT ... .. FEC .. KPGV .... CIE.MSQVCNGKKDCDDGKDEGKG.C 3 AgVgR7 C.GRDT ..... FEC .. GPGE .... CIP.VAKLCDGRRDCTNGHDEEGA.C 3 DmYPR8 C.RPHL ..... FDC .. QDGE .... CVD.LSRVCNNFPOCTNGHDEGPK.C 3

LpR LmLpRl C.TLRQ ..... FQC .. ANGH .... CIP.LTWMCEGEDDCGDNSDETNAVC 5 AaLpRl C.SERQ ..... FRC .. NDGH .... CIH.VSFVCDGEADCSDGSDEHSREC 6

LmLpR2 C.TOQE ..... FRC .. NNGR .... CIP.SHWQCDNEKDCADGSDEIPQVC 4 AaLpR2 C.SODK ..... FRC .. KSGR .... CIP.KHWQCDGENDCSDGSDEDSEKC 4

LmLpR3 C.ASDE •. , .. FTCRTAPGE .... CVP.LAWMCDDNPDCSDGSDEKA .. C 3 AaLpR3 C.SSEE ..... FTCRSGTGT .... CIP.LAWMCDQNRDCPDGSDEMS .. C 3

LmLpR4 C.RSDE ..... FTC .. ANSK .... CIQ.QRWVCDRDDDCGDGSOEKD .. C 4 AaLpR4 C.RSDE ..... FTC .. ANGR .... CIQ.KRWQCDRDDDCGDNSDEKG .. C 4

LmLpRS C.APETE .... FNC .. SDNN ... MCIT.ARWQCDGDLDCQDGSDEQG .. C 8 AaLpRS C.DPLKQ .... FAC . . SENY .... CIT.SKWRCDGEPDCPDGSDERG .. C 10

LmLpR6 C.LPRE ..... FEC.LDRMT .... CIH.QSWVCDGDRDCPDGSDEDVSRC 4 AaLpR6 C.LSLE ..... YQC.SDRIT .... CIH.KSWICDGEKDCPQGODEMPPIC 4

LmLpR7 C.RPDQ ..... FQC . . RNRI .... CIP.GHLHCSGHADCSDGSDEEN .. C 6 AaLpR7 C.RPDQ ..... FQC .. KKOKT ... CIN.GHFHCNGKPECSDGSDEVD .. C 6

LmLpR8 C.DPKTE .... FEC .. GGGM .... CIP.LSSVCDKKPOCPNWEDEPQEKC 4 AaLpR8 C.NPKTE .... FOC .. GGGM .... CIP.LSKVCDKKPDCPEFQDEPNDKC 4

Con aen a C. xxxx . · • • • P'XC • • xxGx • • • • CX:x • XXXXCDGx:xDCXDGSDB. xx. C

fig. 2. Ahgnmcn~ of Cla~ J\ module ~ucnccs lr~m msc.:t I DLR· uperfam1ly receptors known to cndocyto~c yolk protein prccul"\or> in10 OOC)'tc Sequences are paired ""h tho c of homolo ous position' m closely· related rcccptol' Modulei. arcl numbcn:J d lrom !'!·terminal to c• tc nnmn 1 pos111og n in module clusters Consensu~ ~cqucncc rc•ca s rc\1 uc:s thllt arc imn.•nam in v1 l'-1 ,.- momtom1ng global tcniary trueturc. VaR. "tcllogcnm receptor: • • )'O a c i ()'olk protein re<:cptor) L R 1 rcceplllr, Pa. P;:r1p/om·tu ami:rl(<1t1<1 (Amcncan cockma hi. Ag. A•rophdN &u,,,h1,,, 1 ~t ' ipophonn Aa, .~""" aegiplt (ycllo"'·fc\cr mosqu110J, Om, !Jrwoph//a ttU'/anog,,.,..,. (fru~~~u110): INSECT Vil E tNIYOLK PROTCt RfCFPTOR 239

another and do not direct nteract (Bieri et al.. 199 ; onh and BlncklO\\, 1999; Beglova et al., 200 I). Linker lengths are en con erved between homologou Cln A module , ~nclud!ng th?se in insec ~p recepto~ (Fig. I), uggc ting that they play 8 role 10 mamtammg proper ctural relationship among the module ( orth and ~lacklow,. 19?9). T~ e lrngths and secondary structure of the linker may be important m ligand bind ng. because they determine the nexibility of the Clas A modules relative to one •mother during a binding interaction and thus the global topology of the entire domain (Bieri et al., 1998; Dolmer et al., 2000; Kumiawan et al., 200 I; Rudenko et al.. 2002). Very short linkers of I or 2 re idues between Class A modules in some proteins (e.g., Tomita et al., 1998) indicate that they occur in an inflexible linear arrangement (Chamberlain et al., 1998). Nevertheless, linkers as short as 4 residues can be flexible (Bieri et al., I 998). In other ca es, the linkers can be quite long; for example, 3 of the 4 linkers between the 5 Class A modules in the nematode VgR are unusually long, ranging from 20 to 32 residues (Grant and Hirsh, 1999). In contrast, the average number of amino acid re idues comprising the linkers in insect VgR/Yl's is about 7, and in LpR's is about 5. The lengths of linkers in homologous positions in locust and mosquito LpR 's are well conserved, but they can be quite variable among insect VgR/Yl 's (Fig. 2). Cryo-electron microscopy of the bovine LDLR reconstituted in lipid vesicles revealed images of the extracellular domain that were either stick-like, bent stick-like, or Y-shaped (Jeon and Shipley, 2000a). The authors hypothesized that the stick-like and bent stick­ like images represent different rotational views of the Y-shaped receptor. The two anns creating the Y-shaped images are part of the ligand-binding domain (Jeon and Shipley, 2000b), and suggest that some of the modules arc ~olded back on one another, presumably with linkers acting as hinges (Jeon and Shipley, 2000a,b).

C. Binding Interactions

A large body of experimental evidence indicates that the ligand-binding do~ains of LDLR-superfamily members are primarily, though perhaps not exclusively, located in one or more cl u tcrs of Class A repeats (reviewed in Sappington and Raikhel, I998b). The ability of soluble Class A module cl usters or cluster fragments to bind ligands supports the relative independence of this domain (Marlovits et al., l 998a; Vash et al., 1998: Mikhailenko et al., 1999; Koch et al., 2002; Li et al., 2003). Available evidence indicates that ligand binding almost always involves multiple contact points acros multiple Class A modules (Gliemann, 1998; Rettenbergcr et al.. 1999; Doi mer et al., 2000, Herz and Strickland, 200 I). In the multiclustcr receptors such as LRPI 'sand LRP2's the different Class A domains act independently and can btnd different ligand imultancously (Hussain et al.. 1999). Some ligands recognize ttcs m different clusters, and may even bind modules from two cluster. 1multaneou ly (Mikha1lcnko et al., 200 t ; llerz and 240 RI PROOl!CTl\'E BIOL

tncklnnd, 200 I) In cn'e \\here the amc hg d recognize different receptors 1n the LDLR-supcrfam1ly, the receptor bin (Fig. 3) (Dolmer et al . 2000; Koduri and BlackJo,.,,, 2001 ). The remaining re iducs are variable, and the length of the loop created by the disulfide bond can vary as well (Fig. 2) (Oolmer et al., 2000; Simonovic et al., 200 I). Most of the side chain of the component re idues are surface­ exposed, so that variation in the primary sequence can be translated into variable urface topographies, charge distribution, and hydrophobic patches (Dolmer et al.. 2000; Simonovic et al.. 200 I). These surface features provide the potential points of interaction with ligands, and it is the difTenng arrangements of these unique modules within and aero s clusters that account for the wide variety of ligands bound with high affinity by LDLR-superfamily receptors (Hus ain et al., 1999; Rettenberger et al.. 1999; Willnow, 1999; Dolmer et al., 2000). Little is known about ligand-binding interactions in insect VgR/Yl's and LpR's. Insect VgR's bind their cognate Vg ligands with high affinity (Raikhel and Dhadialla, 1992; Sappington and Raikhel, I 998b), with dissociation constants ranging from 200 nM for the membrane bound VgR of the cockroach Nauphoeta ciner~a (Konig et al., 1988) to 15 nM for the purified VgR of A. aegypti (Sa.ppmgton et al., 1995). Many lines of evidence suggest that positively charged residue on the surface of ligands interact with patches of negative charge on the urface of Class A modules in LDLR-type receptors (Wilson et al.. 199 J; Krlimer­ Guth et al., 1997; Gliemann 1998; Hom et al., 1998; Rodenburg et al.. 1998; Raffa! et al., 1999; Ranganathan et al., 1999; Li et al., 2003). In the locust, derivitization of basic residues in Vg eliminated binding to the VgR (Rohrkasten and Ferenz, 1992). Suramin abolishes binding of insect Vg's to VgR's (Rohrkasten and Ferenz, 1987; R6hrkasten et al., 1989; lndrasaith et al.. 1990; Dhadialla et al., 1992; Sappington et al.. 1995) and Lp to LpR (Tsuchida and Wells, 1990). Because it is a polyanion, suramin has been assumed to act as a nonspecific competitor for positive charges on the ligand, but there is evidence that it specifically destabilizes ligand-receptor complexes (Vassiliou, 1997). Li et al., (2003) showed that an 84-ammo acid fragment of Vg from the fish Oreochromis aureus pcc1fically binds a ite in the VgR defined by the first three module in its single eight-module Clas A clu. ter Alignment of the Vg fragment with the LDLR-bmdmg region of human apoB and apoE revealed a conserved motif in the Vg's of 26 other animall. including 11 m.,ect . S1te-d1rected mutagenes1s of the II. K, and K re'>1dues in the li!'lh .,equcnee HL TKTKDL revealed that the K at position 4 attenuated binding to the VgR (L1 et al , 2003). The consensus in m eel., 1\ (I· D)(I V)(T V)K( f S)KN(Y r- ). Tim motif is found in a IN ECT VITI of NI YOLK PROTf!J!\ RE l PTOR 241

Fig 3. Conscn us teniary structure of Class A modules from insect LDLR- superfam1ly receptors known to endocytosc yolk protein precursors into oocytcs, based on con el'\ cd residues (see Fig. 2) and sol~cd truc.turcs of modules in other supcrfamily members. Re~idue (circles) are numbered from the N- term1nu to the C-terminus of the module (excluding linker re 1due ). and con erved re 1ducs are 1od1catcd. Shaded circles specify con crved re idues that contnbute to the mall hydrophobic core ( haded ellipse) of the module. Dashed hne identify res idues that coordinate a Ca++ ion (black circle). wluch IS necessary for stabilizing the structure of the C-tcrmmal loop. 01 ulfide bonds between the highly conserved cystcinc residues arc indicated by a dark vgzag hne. homologous position among all insect Vg sequence in conserved subdomain I, which places it in the small subunit of the A. aegypti Vg (Chen et al., 1997; Sappington et al., 2002). Other domains of A. aegypti Vg must be involved in binding VgR, however, because both large and small subunits bind the VgR independently and with less affinity than the intact protein (Dhadialla et al. . 1992). Interestingly, the YP's from D. melanogaster contain similar motifs, uch as HKLRRVTG and IVAKSKNT in YPI. lt was long assumed that the conserved negatively charged residues in the Class A modules directly interact with positive residue on the ligand surface during binding (Sildhof et al , 1985; Brown and Gold tein, 1986; Rllhrkastcn and Ferenz, 1992), but the involvement of the e residuei. m Ca coordination (Fig. 3) has suggested that they may not be available for ligand binding (Fass et al.. 1997; Sappington and Raikhel, 199 b; Li et al. . 2003). Nevertheless, it appears that negatively charged surface patches on Clas A module are pre ent and nece ary for ligand binding (Bajari et al.. 199 ; Hussain et al., t 999; North and Blacklow, 2000; Andersen et al. . 2000, 20010,b) and that even the conserved re idues involved 242 RJ.!PROOl:C."lWE BIOLOGY Of IN\ BRATES in Ca coordmauon can stall mtcract with a ligand, with an attenuated charge potential {lnnerarity. 2002; Rudenko et al, 2002). H) rophobic interactions also can be important (Warshaw ky et al., 1995; Dolmcr r a 2000), and it is becoming clear that both electro ta11c and hydrophobic corn onents can be involved amultaneou ly m hgand-bmding (Dolmer et al 2000

Ill. CLA B EGF-TYPE MODULE

Superficially, the Class B EGF-type module are structurally similar to the Class A module • in that they are about the same size and their global structure is maintained by di ulfide bonds among six highly conserved cysteine residues. However, the pattern of bonding between the cysteines (C l-C3, C2-C4, and C5- C6) (Campbell and Bork, 1993) is different (Fig. 4), as is their global domain structure and function . In insect VgR/Yl's and LpR 's. as in other LDLR­ superfarnily receptors, Cla s B modules are located in predictable location relative to other domains. A pair of modules is found directly behind each cluster of Class A modules, and singlet Cla s B modules follow each YWXD ~-propeller (Fig. l). In the latter case, the N-terminal region of the Class B module packs tightly and extensively against the C-terminal region of the YWXD ~-propeller domain creating a quaternary structure (Jeon et al., 2001). In the cockroach VgR sequence deposited in the database (Acc. No. BAC02725), only parts of the expected Class B modules flanking the second Class A domain are present, but confirmation of this sequence awaits publication by the authors. Some Class B modules bind a Ca++ ion and some do not (Kurniawan et al., 200 l ). A Ca++ ion binding motif was identified by Mayhew et al., ( 1992) beginning in the linker region between tandem Class B modules:

(D/N)X(D/N)(E/Q)X"(D/N)• X4(Y IF) where (DIN)* is a ~-hydroxylatcd residue (Rees et al., 1988; Stenflo, 1991 ). lnsect VgR/Yl's and LpR's contain this motif and presumably bind Ca • (Fig. 4). Consen us residues for ca+· binding are absent in the first module of the pair and in all singlet Class B modules. However, the first module of the pair in insect LpR's contains a modified con ensus similar to that found in the mammalian LDLR which binds Ca' ~ (Fig. 4). Even though there are fewer residues to coordinate the ion, the conserved aromatic ring of the con ensus residue (Y/F) is thought to shield the Ca ion from the solvent (Kurninwan et al, 200 I) Thss residue may also serve as a recognition . stc for the enzyme that ~-hydroxylate the (DIN) residue (Slenflo et al., 1987). Unhke Class A modules, the bound Ca ion in Class B modules docs not serve to !>tabahze individual module !>lructure. Instead. its position impart rigidity to the hnkcr between module~ (Smallridg~ et al . 1999. Kumiawan I) In addstson. there s!> a hydrophobic 1nterac11on between a con erved I 200 et a ·· · the fir-.t module and a G re\I" d uc in· t he <;econd mod u I e aromauc re 1d ue 10 -

l'li ECT \'ITI.LLOGI·:-.IN YOLK PROTfl~ RH l·PTOR 243 (Fig. 4). \\hich al o re tnch movement of the two module rclati\.e to th (K · · I 2 0 ne ano er unuawan et a .. 00 I; Saha et al.. 2001) . The •.mportance of the!lc module to the function of LDLR - uper1amllr · y receptors 1 underscored by the large number of natural mutations ·n th " th I d · . 1 1 region .at ea to gcncuc defects m vertebrate (Kumia\\an et al, 200 I Saha et al 200 t) L1k th Cl · A od ' ., · e c ass m ulcs. there are only a few con ervcd re idue . which determine module ~ructure and intermodule packing. Thu , variation can be high at mo t position m Class B modules, and different numbers of residue in the loop region arc tolerate~. ~o t mutations in the Class 8 domain that affect receptor function or .trafficking disrupt the disulfide bonds, Ca ~ binding, or turn connecting anllparallel ~-s heets (Kumiawan et al., 200 I; aha et al., 200 I). A mutation of the first cysteine in the third EGF repeat to a erine in the chicken VgR lead to mi folding of the protein and its degradation (Bujo et al.. 1995). There is ome evidence uggesting that Class B repeats in LDLR- uperfamily members arc ncce. ary for ligand binding, but the effect is probably indirect (reviewed in Sappington and Raikhel, I 998b). The fish VgR Cla s A module cluster is sufficient by itself to bind Vg (Li et al., 2003).

IV. YWXD ~PROPELLER DOMAI

A major portion of the extracellular domain of insect VgR/YI 's and LpR' consists of a domain containing the short recurring sequence YWXO. The X is o~en a T residue, and the Y can be substituted with an F. Until recently, the function and structure of this prominent domain were virtually unknown, and boundaries of the repeat that make up this region had not been identified. Usually only. fi~e YWXD motif arc clearly identifiable per domain, because in the first rcpc~t, .11 is replaced by widely divergent equences (Fig. S) (Springer, 1998). Thus, ~t is comm~nl.y reported (even till} that there are five YWXD repeats per domain, though II ts now known that there are actually six repeats (Springer, 1998; Jeon et al.. 200 I). Sappington et al .. ( 1996) faced the same difficulty in identifying the repeat borders, and reported that there were 13 complete and 5 partial YWXD repeats present in the A. aegypti VgR, when in reality there arc 18 complete repeats (Fig. 5). Each of these repeats represents one of six blades in a ~-propeller structure (Fig. 6) predicted for these domains by Springer ( 1998) and veri tied experimentally by Jeon et al.. (200 I). The ~-propeller fold creates a rigid barrel structure when viewed from the side, and a disc shaped structure with a central tunnel when viewed down its central pseudo-rotation axis (Fig. 6) (Fulop and Jones, 1999). The YWXD motif residue themselves appear to be involved in hydrogen bonds and serve to orient adjacent ~- sheets (Springer, 1998). Unlike Class A and Class B domains, the repeats in the YWXD domain arc not themselves modules; in lead the entire domain of six repeats is the unit involved in evolutionary shuffi ing (Springer, t 99 ). LpR's VgRNl's N t

e '°0 c0 ~

.... C'l'I Vl

4 Fig. · Consen US amino acid sequences of EGF Class B module tandem pairs from insect VgR/Yl's (Schonboum c1 al. . 1995; Sappington et ul.. 1996; Ace nos. BAC02725 and EAA06264) and insect LpR's (Dantuma et al., 1999; Cheon et al. 2001). Shaded lines connccuna cystcin residues indicate disulfide bonds (Campbell and Bork 1993) (placement of lines over or under iniervcning sequences is arb11rory) • , l}-hydroxylated residue. Shaded circl~ ind1carc residues· 1mphca1ed· in Ca...,' -binding conscn us mottf (Mayhew et al . 1992) L ong d ns h c d I me ind ica t cs re"'·due s involve d 1n hyd rophobic 1ntcract1on (Kum111wan e l til 2001. Saha <'I ul . 2001) 245 I INSECT VITI l I . YOLK PROTl rN RECFPTO Repeat: 1 ------@--Y - --@------Y------S-8---G F

2 - -@YWTD------@------S ---@- SG@G-PE-~A@DW@T FSE T T D S

3 -N@YFSD- - -- -@-@C-----RCA-@@------P--@A@-P-· WT H

4 G-@FY------T-@-RA-MDG----@@@-D------G@-@D--· W S L E

5 --@YW-D- --- -@E-@---G---R-@--D-@K-P--@A@-- FF H E R

6 --@YWS---T--@---C--Y------@------@-@---- FYT S F

Fig. S. Consensus sequence of each of the six YWXD repeals m the three ~propeller domains of inscc1 VgR/Yrs. The boundaric of the rcpcais follow those 1den1ified by Springer ( IQQS).

This domain has often been described as a "spacer region'' between Class A binding domains, although there is little justification for this contention beyond a lack of knowledge of its function (but see Jeon and Shipley, 2000b). However, as has been pointed out (Sappington and Raikhel J 998b; Springer, 1998), the sheer prevalence of this large domain in LDLR-superfamily receptors and many other proteins argues that it must be of functional importance. In addition, 34% of the known mutations that cause familial hypercholesterolemia in humans are located in the YWXD domain of the LDLR (Jeon et al., 200 I). A G ~ E mutation in the fourth YWXD repeat of the nematode VgR apparently causes misfolding, and the receptor never makes it to the oocyte surface (Grant and Hirsh, 1999). Proper folding and intracellular trafficking of YI and other LDLR-family members in Drosophila is mediated by a chaperone called boca, an protein (Culi and Mann, 2003). It is likely that boca is involved in correct folding of the YWXD domain rather than of the Class A or Class B domains (Herz and Marschang, 2003). Boca homologues have been identified in nematode, A. gambiae, and mammals, and is thought to be of universal importance in folding and trafficking LDLR-superfamily proteins (Culi and Mann, 2003). When an LDLR-superfamily receptor binds a ligand, it is internalized in early cndo omes which fuse to form late endosomes where dissociation of the receptor/ 246 liga nd complex take pince. In the case of A a ri, these endo ome are transfonncd into yolk bot.hes where Vg is accumulat id crystallized as vitellin (Ra1khcl and Dhadialla, 1992; Sn1gircv kaya ct al. 1997 ,I '· The di ociatcd VgR's arc recycled to the oocytc urface in tubular compartm ts that bud ofT from the trans1uonal yolk bod) ( nig1rev kaya et al. . 1997b) S1m1 · recycling compartments contammg the Drosopl11la YI ha\c been ob ervcd a.s wdl <;,chonbaum et al. 2000). The mechani m for receptor ligand di oc1at1on involves acidification of the endo ome, in which the pl I drops below 6.0 (Mcllman et al., 1986; Brown and

1'1g 6. 1l omology 1ruc1urc of lil'\I J}-propcller domain of cockroach VgR ploucd on sol ed (POD c n1 ry codes I 1jqA ond I 1Jq8) of 1h1 \ domain in LOI R. View 15 down ihc CCnll"lll p"' d lcmplotcs A . d d b 0 \CU 0-rOt!lllOO axis "·sheets arc eno1c Y 01 nbron • and reveal 1hc '" 'hlad~ ol lhc propeller c using SWISS-MODI L l(.ue' and Pell"<:h. 1Y971 . hur www UJ'bY Ql'JI pJtn on~irucied I"< ECT VITl:Ll I ' YOLt..: PROTfll' RECI:PTORS 247

Gold tcin, 19 6; Rudenko et a 1 • "'002). \\.'hen the domain containing the tandem EGF Clas B repeat and the 'I' \\ XD repeats arc deleted, LDLR and VLDLR can ~till bind and mtcmah7c hgan :I but dissociation of the ligand from the receptor In the endo ome does not Ot;cur (Davis et al. 1987b; van der We thuyzen et al. . 1991, M1kha1lenko et al.. 1999). Becau e of the imponance of Ca bindfog to ~odule structure and receptor funcuon, It \\as hypothesized that a drop m pH might tllrate away the Ca ion causing confonnalJonal changes in the Cla A or Class B repeats that would re ult m a lo s of affinity of binding site in the receptor for ii) ligand (Fas et al., 1997. Brown et al., 1997; Dirlam-Schatz and Attic, 1998). However, Simonovic et al., (200 I) found that the affinities of Class A repeats for Ca were still too high at pH 5 to promote di oc1ation. In an exciting breakthrough, Rudenko et al., (2002) analyzed the crystal structure of the extracellular portion of the LDLR at pH 5.3, and discovered a urpn mg mechanism for ligand dissociation at low pH. The ligand bindmg domam looped backward and bound the YWXD P-propeller domain along an extensive interface involving Cla s A modules 4 and 5. This structure suggests that at low pH, the P-propellcr becomes an intramolccular ligand with higher affinity than the internalized ligand, which is relca ed through a displacement reaction. The rigid pair of Class B EGF-typc modules provide the necessary pacing for proper interaction of the Class A repeats with the P-propeller, explaining the inability of a receptor to dissociate from its ligand when these modules are absent (Davis et al., l 987b). It is likely that this function of the YWXD P-propeller as an "ac'.d­ release domain" (Rudenko et al.,2002) is characteristic of other LDLR-superfamily members (fnnerarity, 2002). Jn most insect tissues, LpR bind and internalizes Lp wilh its lipid cargo (van der Horst et al., 2002). Interestingly, the LpR/Lp complex does not dissociate in the endosome, but are recycled together to the cell surface (van Hoof et al., 2002). However, in the oocyte, Lp is dissociated from the LpR and is stored in the yolk along with Vg (Sun et al.. 2000; Telfer, 2002; see van Antwerpen, this volume). Another possible function of the YWXD domain which must be considered lies in protein-protein interactions, which may include ligand binding. Springer ( 1998) noted that there is surprising conservation of primary structure between certain YWXD domains in the LRP's of humans, chickens, and nematodes. This, along with the known ability of YWXD ~-propellers to bind other protein (Fox et al. . 1991; Mayer et al., 1993; Springer, 199 ), ha lead to speculation that this domain may be involved in ligand-binding interactions, e pecially in the larger LDLR-superfamily receptors (including in ect VgR's), which carry multiple YWXD domains (Springer, 1998; Fl.ll6p nnd Jone , 1999; Loukinova et al., 2002; Strickland et al.. 2002). 248 REPRODUCTIVE BIOLOGY OF l 3RATES

V. 0-LI KED GL YCO \ l DOMAJN

In the LDLR and VLDLR, there is a domain bet\ 1e last Class B repeat and the membrane that 1 glyco ylated with 0-hnked s • presumably on some or all of the Sand T re idue in this domain (Ru cl et a 1984; lijima el al .. 1998) 0-hnked glycosylation has been demonstrated in oth 1LR-superfamily mernbets. but their location not specifically determined (Jok101,;'1 / al., 1994; Kobayashi et al., 1996; Ziak el al., 1999). There is no clear consensus amino acid motif for 0- linked glycosylation, but the S and T residues arc often clustered, and docking of the glycosyltransferases may depend on local negatively charged residues (especially E) and presentation of the S or T residues in an appropnate ~-tum conformation (Hansen el al., 1998). The length of the domain between the last Class B module and the transmembrane domain varies greatly among LDLR-farnily receptors, and some contain putative 0-linked glycosylation sites while others do not. In the Aedes and cockroach VgR's, this domain is a little over 30 amino acids long and contains 9 and 6 Sff residues, respectively, whereas only 3 T residues are found in Anopheles VgR and 2 S's in Drosophila Yl. ln contrast, the 0-linked sugar domain is over 2SO residues long in the Aedes LpR and 26% of the residues are S or T (Fig. I) (Cheon el al., 2001). The same region in the locust LpR is similar in size to the insect VgR's and contains 5 Sor T residues (Dantuma et al., 1999). ln both chicken (Bujo et al., 1995) and two species of fish (Prat et al. , 1998; Li et al., 2003), the 0-linked sugar domain is spliced out of ovarian-specific VgR/VLDLR variants. Alternative splicing of this region in other LDLR-supcrfamily members has been reported (Jokinen et al. . 1994; Martensen et al., 1997; Magrane et al., 1998; Nakamura et al., 1998). There are many biological functions of 0-linked sugars (Hansen et al., 1998), but their role in LDLR-superfamily receptors is unclear. There are two main hypotheses, and they arc not mutually exclusive. Jentoft ( 1990) proposed that clusters of O.linked carbohydrates tend to induce a stiff and extended conformation of the core peptide. Thus, it is often suggested that the 0-linked domain of LDLR­ superfiunily receptors may hold the receptor away from the membrane to promote free interaction with the ligand (Goldstein et al., 1985; lijima et al., 1998; Hussain et al.. 1999). However, removal of this domain had no effect on ligand binding by the LDLR (Davis et al., 1986). Furthermore, the absence of this domain in vertebrate VgR's and it ab ence or reduction in some insect VgR's, Yl's, and LpR's, argues against th1 being an important function. Alternatively, the 0 -linked domain may prevent cleavage by membrane-bound proteases (Kingsley et al.. 1986; Kozarsky ct al, 1988; Ehlers et al., 1996; Mullberg et al., 1997). A soluble fTagment of human VLDLR 1s shed by HeLa cells in culture, and this fragment is from the splice-variant without the 0-linked domain (Marlovits et al., t 998b). Shedding of the VLDLR extracellular domain from the cell surface by proteolysis was much greater for the 0-hnked- negatt"\C phce-vanants compared INSECT Vil E.NN YOL I>.. PROTr I RECEPT R 249

10 vanants with the dom.. · ma et al· 199 : Magran ~ et al . 1999) oluble fonns of LRP are present t he era of a number of animal , including mollusc , but the mode of cleavag rom the cell urface 1 unknown (Quinn et al., 1997; Jung et al., 1998; Gri msl y ct al, 1999).

\ J. CYTOPLA Ml T IL

C-terminal to the single-pass tran membrane domain is the cytoplasmic domain or "tail". The tail itself is not considered a module in LDLR-superfamily receptors, although splice variants have been identified in which a 33-59 amino acid stretch 1 insened within this domain (Brandes et al., 1997; Stockinger el al., 2000; Liu el al.. 2001). In insects, the length of the cytopla mic tail ranges from 58-60 amino acids in LpRs (Dantuma et al., 1999; Cheon er al.,2001), to 89-103 residue in VgR's (Sappington et al., 1996; Acc. no. EAA06264), to 161 residues in YI (Schonbaum er al., 1995). The cytoplasmic domain is respon ible for binding the adaptor proteins that in turn assemble other protein machinery necessary for endocytosis, such as clathrin. The cytoplasmic tails of LDLR-superfamily receptors contain a variety of internalization signal motifs that can be involved in binding adaptor proteins (Ohno er al.. 1995; Heilker el al., 1999; Li et al., 200 I b, c; Bonifacino and Traub, 2003), and the type of signal used depends on the receptor. Endocytosis of insect VgR's, YI , and LpR is a clathrin-dependent process (Telfer el al., 1982; Raikhel and Lea, 1985; Rt>hrkasten and Ferenz, 1987; Raikhel and Dhadialla, 1992; Schonbaum et al., 2000; Bownes and Pathirana, 2002), and the same is likely true for insect LpR's (Sun el al.. 2000; Cheon el al.. 2001). There are two main clas es of internaliz.ation motif, tyrosine-based and dileucine based (Marks et al., 1997; Heilker et al.. 1999; Bonifacino and Traub, 2003). The internalization motif, NPX(Y/F), is the most common tyrosine-based signal found in LDLR-superfamily members, and early experiments howed that the Y is critical to endocytosis of the LDLR, although an F may be substituted (Davis et al.. 1987a; Chen el al., 1990). The vertebrate LRP I contains two NPXY motifs, but a different tyrosine-based motif, YXX0 (where 0 is an amino acid with a bulky hydrophobic side chain) (Trowbridge et al.. 1993) was shown to be more important in internalization (Li et al.. 2000). The Anopheles VgR contains a sequence in its tail that matche this motif, YAQV. It is often casually remarked in the literature that oil LDLR-superfamily receptor contain at least one PXY antemalizauon motif in the cytoplasmic tail, but .this is ine~rrect (Sappington and Raikhel, I 998b; Hey et al., 1998). Although the 1ns~c t LpR s. and the cockroach VgR each contain an NPXY or NPXF sequence, mosquito VgR and the Drosophila YI are missing the critical Y/F at the homologous pos111on ( appangton and Ra1khel 1998b) l t d h • . ns ea , t e e receptors 250 Rl!J>ROD CTIVU BIOLOGY OI INV BRATIS contain one or more d1lcucine mouf! ( appington 996), which are common mtemahzatton ignal m a '' 1de vancty of membmn nnmg proteins (re\iewed 10 Bonifacino und Traub. 2003) One of the L n be replaced by I or \t (Kirchhau en. 1999) and po. ibly an A or V ( an O\ I nd Bakke, 1994). The first L 1 usually preceded by a polar residue, and a •1vely charged residue is usually located 2-4 po 1t1on further upstream ( K1r 1h usen, 1999). The be~t matchmg motif.c; m the m ect VgR's are located near 1 e C-terrninus, and ma homologous po . i11on m the interior of the longer tnil of the Drosophila YI (Fig. 7). The polar and charged residue around the LL moti f arc thought to en ure exposure of the LL doublet to the solvent (Kirchhausen, 1999). A dileucine motif in the human insulin receptor is involved in clathrin-mc

PaVgR DGSDKAPLIH-COOH AgVgR DDDLHERLIV-cooH AaVgR RDDPLQRLIL-coo11 DmYl GDPMAQELLL- (6laa)

Fig. 7. Alignment of probable dileucine intemalitation signals in in~cct VgR/Yl's. Pa, Perip/011eta amerlca110 (American cockroach); Ag, Anopheles gambiae (malaria mosquito); Aa, Aedes aegypti (yellow fever mosquito); Dm, Dro.sophila mela11ogt1J1cr (fruit fly) .

There arc other motifs in the cytoplasmic tai ls of msec1 ypp receptors that may be involved in internalization. Denzer er al, ( 1997) analyzed a heptapeplide motif in the manno e 6-pho phate receptor (AKGMEQF, where the A, E, Q. and F were es ential) that act m concert with a d1leucme and YXX0 motif as an mtemahzat1on sequence. The Drosophila YI tail contain. a similar sequence, AKSAGQF, tn the C-tcrminal portion of the tail which i. not homologous to the horter insect VgR tail The cquence NPFX "' ~ D can direct cmcicnt uptake of 11 1 the Kex2p receptor m yeast (Tan er al. 1996, Dunn and I ltckc, 200 I; Howard et al , 2002). A 1milar motif (NPFD) i found m the cytopla~m 1 c tail of the cockroach VgR. The Aede.\ VgR cytoplasmic tail contatn)i n Src-homology 3 ($113) binding motif, PXXP (Sappington and Raikhel, 1998b), whic h t~ ubo pre~cnt in the tails of some other LDLR-supcrfomtl}' receptor. (I l;tllm ('r al. I 996, Sun and Sou tar, __, l\H.fVIJI Ll l:'I H}flo;'.l'ltOlll RECIPlO

l999). uch domains ma) p role in clJthrin-dcpemknt an11.~m:ihl'at1on through their recn.11tmcnt of rhc t) ro nc kina.,c c- n .• \\hich in tum dl\Dtc the \:nl')me (d)namin) re pon ible for pinching off the clathrin-coatcd pll from the pla .. ma membrane (Ahn et al , 1999 Wilde et al 1999: 1illcr t'/ al.• 2000). Recent!) II "a., shown that phosphor lntwn of a residue in the cytopla,mil..· tail regulate' l\.'CC~ ror-mediated endocytthl of LRPI (Bu et al. 1998: 1.1 et al.. 2001a). unJ ligand affintty of the extracellular domatn of VLDLR ( akthi\.cl et al.. 200 I) ·apptngton et al., ( 1996) 1dcn111icd thrcc potenttal site of phosphol)'lmion in thc cy t oplu~mic tails of the Aedes VgR and Drv.wphila YI Recent studie have shown that the cytoplasmic domam., of many LDLR­ superfamily receptor.. have domains that interact '"irh a \anery of other protem'> involved in cellular signal transductton cascades (I lcr1 and trickland. 200 I. Lt et al.. 200 lb). Sll3 binding motifs are implicated in such cascades ( tockmgcr et al· 2000). and PDZ-binding motif. (Sff)XV. have been 1dent11icd m megahn. and may operate in signallmg cascades (Gotthardt et al . 2000; Takeda et al. 2003). The cytoplasmic tail of the cockroach VgR contams a DY cquencc. matching the PDZ-binding consensus. The PXY internalization sequence 1s al o 111 \olvcd 10 signalling cascades in LDLR-superfamily members (Gotthardt et al.. 2000; Bame et al., 200 I; Loukmova et al.. 2002; Ben ha yon et al. 2003 ). As indicated above, a tantalizing number of potential internalization and signalling molifs arc present in the cytoplasmic tails of insect VgR ·s, YI. and LpR 's. However, much experimental work remains to be done to characlcrize the role of these potential signals in insect receptor function. The rapid progress being made in the vertebrate descendants of the e proteins will be of t:,rrcat help in guiding future research on this cri1ical domain in YPP receptors.

REFERENCES

Adams, M D., Ccln1kcr, S E . llolt, R. A.. Evan•. C A .. Gocaync, J D., Amanaridc,, P G .. Scherer, S. I:. .. L1, P w .. llO'lklll . R. l\ . and Galle. R. F. (2000). ·The genome 3C<1ucnce of Drosophila melanogu~ter'. St.·n·nct 287, 2185-2195. Ahn. S .. Maudsley, S .• Lunrcll, L. M Letko.-nz, R. J .• and 03llka, Y (1999). ' rc-mediarcd l)'rosme pho phorylauon of dynamm 1 required for bcrJ2-adrcncrg1c rcccpror m1ernahza11on and mnogen-acll\alcd pro1cm kinase s1gnahn1f. J Bwl Chem. 274. I 185-1181! Ahschul, S F .. Madden. T. L. Schaller. A A. 7h.tng. J .. Zhang. 7 .. Miller \\, • ond Lipman, D J. ( J 997) ·Gapped BLAST and P 1-BW.\ST· 11 nc\\ gencrauon ol pro1em da1abase search proivams'. v11d,.1c 1<1C'n, 1 1 1 200 1 J 'ldcnr1Jicat1on ol the nunim,11 funcllonnl unn 252 REPRODUCTIVE BIOLOGY OF l!\V RATES

m me low den 1ry hpoprotem receptor-related protem for the recep1or-assoc1atcd pro«tin (RAP). A col\SCf\.ed ac1d1c re:.1due m the complemenr-typc t 1s important for rccogrunco of RAP,' J Biol Chem 275, 21017-21024 Andersen, 0. M , Petersen, H. H., Jacobsen. C .. Mocstrup, S K , M , Andreasen. P A, md Thogcrsen, H C (2001b). 'Analysis of• t"o-donwn lie for me urolunase·cypc plasminogcn ac11va1or-plasm1nogen activator 1nh1b11or- l tn low-densuy-lipoprotem- receptor-related protein'. 81ochem J., 357, 289-296 Bajari, T M., Lmdstedt, K. A.. R1epl, M , Mirsky, V M , N1mpf, J , rbe1s, 0 . S., Dresel, H. A., Bautz. E K., and Schneider,~ J. (1998). 'A m1mmal b111d domam of me low density hpoprotcm receptor farrnly', 8101 Chem. 379, 1053-1062. Bame , H , Larson, B • Tycrs, M • and van der Geer, P (2001) 'Tyrosin hosphorylated low density hpoprotc1n receptor-related protein I (LRP I) associates with the 1ptor protein SHC in SRC· transfonncd cells', J. Biol. Chem .. 276, 19119-19125. Beglova, N., North, C. L., and Blacklow, S. C. (2001). ' Backbone dynamics of a module pair from me ligand-binding domain of the LDL receptor', B1ochemiflry, 40, 2802-28 15. Benhayon, D, Magdaleno, S., and Curran, T. (2003). ' Binding of punfa.'d Reehn to ApoER2 and VLDLR mediates tyrosine pho phorylouon of Disabled-I', Mo/ Brom Res., 112, 33-45. Bien, S., Djord1ev1c, J. T., Daly, N L., Smith, R., and Kroon, P A (1995a). ' Disulfide bndges of a cystcme-nch repeat of the LDL receptor ligand-binding domain', Biochemistry. 34, 13059· 13065. Bieri, S., Djordjev1c, J. T., Jamsh1d1, N., Sm1m, R., and Kroon, P. A. ( 1995b). ' Expression and d1 ulfide-bond connec1iv1ry of the second ligand-binding repeat of the human LDL receptor". FESS le11. 371, 341-344. Bien, S., Atkins, A. R., Lee, 11. T., Winzor, D. J., Saum, R.• and Kroon, P. A. (1998) 'folding, calcium bmding, and structural charactenzauon of a concatcmcr of the first and second ligand· binding modules of the low-density lipoprotem receptor', 81oclremiS11y, 37, 10994-11002. Blacklow. S C, and Kim, P. S (1996). 'Protein folding and calcium bmdmg defects ans1ng from familial hypcrcholesterolcm1a mutations of me LDL receptor', Not Struct. Biol., 3, 758-762. Bomfacmo. J. S.. and Traub, L. M. (2003). 'Signals for sorung of transmembranc proteins to endo3omes and ', Annu. Rev. Biochem , 72, 395-447 Bork, P., and Gibson, T. J. (1996). 'Applying motif and profile searches', Meth. Enzvmol. 266, 162-184. Bork, P., Downing, K., Kieffer, B., and Campbell, I. 0 . ( 1996). 'Struc1ure and distnbution of modules m cxtrncellulnr proteins', Q11or. Rev. Biophys., 29, l 19-167 Bownes, M (1992). ' Why 1s there sequence similarity between insect yolk proteins and vertebrate hpases?', J lipid Res, 33, 777-790. Bowncs, M., and Pathirana, S (2002). 'The yolk proteins of higher D1ptera', m Reprod11c11w! 810/ogy of /nvenebrates, Volume XII • Recent Progress in Vi1ellogenes1f, (Volume Ed . A. S. Ra1khel and T. W. Sappington; Series Eds. K.G. Ad1yodi and R G Ad1yodi). Science Publishers, Enfield, USA, pp. 103-130 Bo"'"11es, M . llurd, H., Busgcn, T, ~ay, D , Alvis, S .. Popovic. B , Bruce, S., Bums. I. Rothwell. K , and W1ll..11bhaw, M (2002) 'Dr0Joph1lo yolk protem produced 1n E. colt 1 accumulated by m®tu110 O\anes', /nsttt Mo/ 810/, 11, 4117-496. Brandes, C'., NO\lk, S, Stockinger, W., Hen, J., Schneider, W J , and Nimpf, J (1997) 'Avian and munnc LR8B and human apohpoprotem (; receptor 2: d11Tercn11ally ~pliced products from corm.ponding gen~', Gtnom1n 42, 1115-191 . Brande , C, Kahr L .• Stocl..mgcr. \\ , lhe~bcrac:r, T .. Schneider, w. J. , and N1mpf. J. (2001). 'Altcmall\C phcmg m me hgand bmdmg domam of mouse Apo( rtcqitor-2 produces receptor

vananl bindmg n:c:hn hut not a 2 -macruglobuhn'. J Bwl Ch<-m, 276, 22160-22169. Brown, M S , and Gol

Ba, G.. Sun, Y . Sch14aru, A I Uoltnnan, D 1 ( IW ) • c:l''C ~Vi la.-: Of rapid increases m functional c rfacc lo" dcru11y hpoprou:in r.:.:ep1t•Mcla1cJ rroie1n'. J. Biol Ch""'. 27.1, 13359-1 I 8UJO, H • Hermann, M . Ka& I O. Jacobsen. L u11awan, S Sunpt. J ~ Yamamoto, T•• and Schneider, W J (19< 'b1cken oocytc growth 1~ mediated by an e1 ht h~ bmJin ~I member of thc LDL icr family', £ MBO J 13, 5165°517.S BuJO, H., L1nd.1ed1, K. '\ , I nn, M, Dalmau. L M .. N1mpf, J. au,J hne1Jcr, W. J ( 19951 'Chicken oocy1cs ar 1a11c cells e~pre different pl11;e "anant of a mult1func11on1I rcccp1or', J 8101 Ch 270, 23546-2355 I. Campbell, I D . and Boric p 993) 'Fp1dcrmal growth factor· hlr.c module!>'. Curr Opin • tru

Davi , C G , van Dncl, I. R., Russell. D. W.. Brown, \1 S . and Gold 11:111, J. L. ( 1987a) 'The lo"' den 1ty hpopro1c111 receptor 1dcnnficatio11 of ammo acid\ in the C)10pla~mic domain requ1ml for rapid cndocyto\I ·, J 810/ Chem.. 262, 4075-4082 Oa\1 • C. G., Gol \V. and Brown, M. S ( l 987b). 'Acid-dependent hgand dissoci:mon and recycling uf L >L receptor mediated b> gro"'th factor homolog) region', .Voture, 326, 760-765. Denzer, K. • Weber, B .. lhllc-Rehfeld, A., Figura, K. V., and Pohlmann, R ( 1997). 'ldenuficanon of three mtemalizauon sequences in the cytoplasmic tail of the 46 kDa mannose 6-pbosphate receptor', Bio,hcm J. 326, 497-505. Dhad1alla, T. S., flays, A. R., and Ra1khel, A. S. ( 1992). 'Charactcnwllon of the solubilized mosquito v11cllogcnm receptor', Insect Biochem. Mo/. Biol. . 22, 803- 1! 16. Dirlam-Schatz, K. A., und Atlle, A. D. (1998). 'Calcium induces a confonnntional change in the ligand binding domain of the low density lipoprotein receptor', J Lipid Res., 39, 402-411. Dolmer, K., Huang, W., and Gctllns, P. G. W. (1998). 'Chnracterin111on of the calcium site m two complement-like domains from the low-density lipoprotcin receptor-related protein (I.RP) and companson "'1th a repeat from the low-density lipoprotem receptor', 8 11x:hemistr)'. 37, 17016- 17023. Dolmer, K .. Huang, W., and Getuns, P. G. W. (2000). · MR ~oluuon structure of complement-like repeat CR3 from the low density lipoprotem receptor-related protein. Evidence for specific

binding to the receptor bmdtng domain of human a 2 -macroglobulm , J Biol Chem . 275, 3264-3269. Doohnle, R. f ( 1995). ' The mul11phc1ty of domams in proteins·. Annu Rn Biochem . 64, 287- 314. Dunn. R, and H1cke. L. (2001). ' Multiple roles for R~p5p-dcpcndc nt ub1qu111nation 11 the intemahzauon tcp of cndocytosis', J 810/. Chem 276, 25974-2591! 1 Ehler.., M R. W , chwagcr, S. L. U., SchoUe, R. R .. ManJ1, G A., Brandt, W F. and Riordan. J. F. ( 1996). ·Proteolytic rclea>e of membrane-bound ang1oten\ 111-<:on\cnmg enzyme: role of the JU' of the ligand bmdmg domam of the low dcns11y hpoprotem receptor'. J. B1of Chem .. 263, 13282-13290. Fass, D., Dlacklow, S., Kim, P. S .. and Berger, J. M. (1997). 'Molecular basis of familial hypercholcsterolaemia from structure of LDL receptor module·, . 388, 691-693. Fox, J. W., Mayer, U.. N1 cht. R., Auma1lley, M. . Reinhardt, D. Wiedemann, II., Mann, K .• Timpf, R., Kncg, T., Engel, J., and Chu, M.-L. (1991). 'Recombman n1dogcn consists of three globular domains and mediates binding of laminin 10 collagen type IV', f'\fBO J , 10, 3137- 3146 FOlOp, V . and Jones, D T (1999). 'Beta propellers: Mructural ng1d1ty ond functional diversity.' Ct1" Opm Stn1ct Bwl, 9, 715-721 Gclhson, G., and l".mmcnch, It. (1978). 'Change in the liter of,uclogcnin and ofd1glycende carrier hpoprotcm m the blood of adult lociista m1gru10r1a'. lmn. T 810d1rn1 8, 403-412. Ghemann. J (19911). ' Rc.:cptor.. of the lo"' density hpoprotcin (LOLI receptor family m man. Mul11ple funclloM of the large family members via interncuon "'uh complex ligand ', Biol Chem .. 379, 951-91>4 , Gold~tcm . J l . Brown, "1 S, Ander..on. R. G \\i , Ru,;.cll , D W .. and Schneider. W. J (1985). ' Rc.:eptor-mcd1atcd cndo91osi~ concepb emerging from the LDL receptor )'~tem ' , Anm1. Rt"> . Ct:fl 810/ , I, 1-39. Gotth.irdt. M , fromin,dorll , M ~ Ncvm. M. F. Shelton, J., Richardwn. J A., Stockinger. W., irnpf, J.. •Ind lieu J (2000) ' ln1crac110~ of the lo"' dcn~uy hpoprotcm receptor gene family w11h cyto,ohi: adaptor and o,calToldprotcins suggc I diverse b1olog1eal functions in cellular ct1mmu111ca11on and •ignal tran..ducuon', J B11>/ Cltcm 275, 2~616-2~624 Grant, n.. and lhr.h, D (1999) 'Rcccptor-mcd1a1cd cndocytO'>I~ in the Cm:norltuhdit/.~ elt'f:OllS OOCyte', \fol 8111/ Cd/. 1O. 4l11-4326 INSECT VITELLOGE f /YOLK PROTEfN RECEPTORS 255

Grimsley, P. G., _Quinn, K. A, Chestennan, C. ., and Owensby, D. A. ( 1999). ' Evolutionary c_on~rvauon of circulating soluble lov. density lipoprotein receptor-related protein-like ( .. LRP­ hke ) molecules'. rhromb. Res.. 94, 153-164. Guex, ·• and Pe1tsch, M C. ( 1997). 'SWISS-MODEL and the Swiss-PdbV1ewer: An environment for comparauvc protein modeling·, Electrophoresis. 18, 27 14-2723 . Hafer, J .• a~d Feren~ H.-J (199 1). 'Locust vitellogcnin receptor: an acidic glycoprotcin with and 0-hnked ohgosaccharides', Comp. Biochem. Physiol., 1008, 579-586. Hamer, I., Haft, C. R., Paccaud, J. P., Maeder, C., Taylor, S., and Carpcnuer, J. L. ( 1997). ' Dual role of a dilcucine mouf in insulin receptor endocytosis", J. Biol Chem., 272, 21685-21691. Hansen, J. E., Lund, 0., Tolstrup, N., Gooley, A. A., Williams, K. L., and Brunak. S. ( 1998). 'NetOglyc: pred1ct1on of mucin type 0-glycosylation sites based on sequence context and surface accessib1hty', Glycoconj. J. , 15, 115-130. Hays, A. R., and Raikhel, J\ $. ( 1990). 'A novel protein produced by the vitellogenic fat body and . accumulated in mosquito oocytes', Rou.x s Arc/1h>es of Developmental Biology. 199, 114-121. Hemkoff, S., Greene, E. A., Pietrokovski, S., Bork, P., Attwood, T. K., and Hood, L. ( 1997). ·Gene families: the taxonomy of protein paralogs and chimeras', Science. 278, 609-614. He1lker, R., Spiess, M., and Crottet, P. (1999). ' Recognition of sorting signals by clathrin adaptors'. Bioessays, 21, 558-567. Herz, J., and Bock, II. H. (2002). ·Lipoprotein receptors in the ner.ous system', Annu Rev. Biochem.. 71, 405-434. Herz, J., and Farese, R. V., Jr. (1999). ·The LDL receptor gene family, apohpoprotein B and cholesterol in embryonic development', J. Nutr., 129(2 uppl), 473S-475S. Herz, J., and Marschang, P (2003). 'Coa,~ing the LDL receptor family into the fold', Cell. 11 2, 289-292. llerz., J., and Strickland, D. K. (2001). ' LRP: a multifunctional scavenger and signaling receptor', J. Clin Invest . 108, 779-784. Herz, J., Gotthardt, M., and Willnow, T. E. (2000). 'Cellular signalling by lipoprotein receptors'. Curr. Opin. lip1dol. . II, 161-166. Hey, P. J., Twells, R. C. J., Phillips, M. S., Nakagawa, Y., Brown, S. D., Kawaguchi, Y. . Cox, R., Xie, G., Dugan, v., Hammond, H., Metzker. M. L., Todd, J. A., and Hess, J. F. (1998). 'Cloning of a novel member of the low-density lipoprotein receptor fomdy', Gene, 216, 103- 11 I. Hjalm, G., Murray, E., Crumley, G., llarazim, W., Lundgren, S., Onyango, I., EK, B., Larsson, M., Juhlin. C., llellman, P., Davis, H., AkerstrOm. G., Rask. L.. and Morse, B. (1996). 'Cloning and sequencing of human gp330, a Ca2•.binding receptor wi1h potential intracellular signaling propcnies', Eur. J. Biochem., 239, 132-137. Holt, R. A., Subramanian, G. M., Halpern, A., Sunon, G. G., Charlab, R., Nus kern, D. R., Wincker, P., Clark. A. G., Ribeiro, J. M., and Wides, R. (2002). 'The genome sequence of the malaria mosquito Anopheles gambiae', Science. 298, 129-149. Horn, I. R., 'an den Berg, B. M. M., van der Meijden, P. z.. Pannckoek, II., and van Zonnevelcl A.­ J. ( 1997). 'Molecular analysis of ligand binding to the second cluster of complement-type repeats of the low density hpoprotein receptor-related protein Evidence for an allosteric component in receptor-associated protein-mediated inh1b111on of hgand binding'. J. Biol. Chem. . 272, 13608-13613. Horn. I. R., van den Berg, B. M. M., Moe:.1rup. S. K., Pannckoek. H., and van Zonnevcld, A. J. ( 1998). 'Plasminogen activator inh1buor I contains a cryptic high affinuy receptor bmdmg site that is exposed upon complc)( formation with tis ue-type plasmmogen activator', n1romb. Haemos1.. 80, 822-828. Howard, J. P. • llunon, J. L.. Olson, J. M., and Payne, G. S (2002) 'Sia Ip senes as the targeting signal recognition factor for NPFX( l ,2)D-mediated endocyto 1s', J Cell Biol, I 57, 3 15-326. Howell, B. W., nnd llerl', J. (200 1). 'The LDL recep1or gene family: 1gnaling functions during development', Curr. Opin. Neurobiol. , II, 74-8 1. 256 REPRODUCTIVE BIOLOGY OF INVERTEBRATES

Huang, W. • Dolmer. K .. and Gemn. P. G. (1999). 'NMR oluuon -tructure of complement-lile repeat CR8 from the low density lipoprotein receplor-rclatcd rrotein', J Biol Chon . 274, 14130-14136. Hussain, M. M .. Strickland, D. K .. and Bak.illah, A. (1999) 'The mammalian low-den uy hpoprotCID receptor family', Ann11 Rev Nutr.. 19, 141-172 lijima, H., M1yazawa. M .• Sakai, J., Magoori. IC ho, M. R., Suzulo, H. Nose, M., Kaw111bayas1. Y.• and Yamamoto, T T (199 ). 'Expression and charactcr....auon of a very low dctis1t} hpoprotem receptor \anan1 laclung the 0-linked sugar region gcnM1ted by ahcmauve sphcmg'. J B1ochem . 124, 747-755 Indra 1th, L. S., Kindle. H., and Lanzrcin, B. ( 1990). ' Solubilwuion. 1den1ifiai11on, and locah.zaooo of vi1ellogenin-bindmg sues in follicles of the cockroach, Na11phoeta cmerea', Arch. Insect Biod1em. Physiol.. IS, 1-16. lnneranty, T. L. (2002). 'LDL receptor's ~-propeller displace~ LDL', Science, 298, 2337-2339. I hii, II., Kim, D.-H., Fujita, T., Endo, Y., Saeki, S., and Yamamoto. T T. (1998). 'cDNA cloning of a new low-density lipoprotcin reccp1or-rela1ed protein and mapping of its gene (LRPJ) to bands 19ql2-ql3.2', Genomics, 51, 132-1 35 Jcntofi, N (1990). ' Why are proteins 0-glycosylated?'. Trend> Buxhem Sci.. IS, 291 -294. Jeon, H , and Shipley, G. G. (2000a). 'Vesicle-recons111u1cd low density lipoprotem receptor. V1 uahzanon by cryoclectron microscopy', J Biol Chem , 275, 30458-30464. Jeon, H., and Shipley, G. G. (2000b). 'Localization of the N-tcnmnal domain of the low denslly hpoprotem receptor', J. Biol Chem., 275, 30465-30470 Jeon, II., Meng, W., Takagi. J., Eck, M. J., Springer, T. A., and Blacklow. S. C. (2001). ' Implications for famihal hypercholesterolem1a from the structure of the LDL receptor YWTD-EGF domain pair', Nat Struct. Biol . 8, 499-504. Jokinen, E. V., Landschultt, K. T .• Wyne, K. L., Ho, Y. K., Frykman, P K., and Hobbs, H H. (1994). 'Regulauon of the very low density lipoprotem receptor by thyroid honnone in rat skeleUI muscle', J Biol. Chem , 269, 26411-26418. Jung, F. F., Bachinsky, D. R., Tang, S. S., Zheng, G., Diamant, D . Haveran, L., McCluskey, R. T~ and lngellinger, J. R. (1998). 'Immortalized ml proximal tubule cells produce membrane bound and soluble magalin,' Kidney Int., S3, 358-366. Kang, Y., Kulakosky, P. C., van Antwerpen, R., and Law, J. H. ( 1995). 'Sequestration of insecticyanin, a blue hemolymph protein, into the egg of the hawkmo1h, Manduca stxto. Evidence for recep1or-media1ed cndocytosis', Insect Biochem. Mo/. Biol., 2S, 503-510. Kawooya, J. K., and Law, J. H. (1988). 'Role of lipophonn in lipid transport 10 the 1nsec1 egg', J Biol Chem., 263, 8748-8753. Kawooya, J. K., Osir, E. 0 ., and Law, J. H. (1988). ' Uptake of the major hemolymph lipoprotem and its transformation m the insect egg', J. Biol. Chem, 263, 8740-8747. Kim, D.-H., Magoon, K., Inoue, T. R., Mao, C. C., Kim, H.-J , Suzuki, H., Fujita, T., Endo, Y., Saeki, S .• and Yamamoto, T. T. ( 1997). 'Exon/iotron orgamzation, chromo ome localization, alternative splicing, and transcription units of the human apohpoprotein E receptor 2 gene'. J Biol Chem., 272, 8498-8504. Kingsley, D. M., Kozarsky, K. F., llobbie, L., and Krieger, M. (1986). 'Reversible defects in 0- linked glycosylation and LDL receptor expression m a UDP-Gal/UDP-Gal Ac 4-epimerase deficient mutant', Cell, 44, 749-759. K1rchhausen, T. (1999) 'Adaptors for clathrin-mediated traffic', Am111 Rev. Cell Dev. Biol. IS, 705- 732. Kobaya hi, K., Oka, K., Forte, T., Ishida, B., Teng, B., lshimura-Oka, K., Nakamuta, M., and Chan, L. ( 1996). ' Reven.al of hypcrcholesterolemia in low-density lipoprotcin receptor knockout mice by adenov1rus-media1ed gene transfer of the very low-density lipoprotein receptor', J. Biol. Chem., 271, 6852-6860. Koch, S., Strasser, V., Hauser, C., Fasching, D., Brandes, C., Bajari, T. M., Schneider, W. J., and Nimpf, J. (2002). 'A secreted soluble form of ApoE receptor 2 acts as a dominan1-nega1ive receptor and inhibits Rcclin signaling,' EMBO J., 2 1, 5996-6004. INSECT VITELLOGENIN/YOLK PROTEIN RECEPTORS 257

Koduri, V., and Blacklow, S. C. (2001). 'Folding determinants of LDL receptor type A modules', Biochemistry. 40, 12801-12807. KOrug, R., Kindle, H., Kunkel, J. G., and Lanzrcin, B. (1987). 'The effect of calcium on receptor­ mediated endocytosis of v11e llogenin in cockroach follicles in vitro', Erperientia, 73, 688. Konig, R., Nordin, J. H., Gochoco, C., and Kunkel, H. (1988). 'Studies on ligand recognition by vitellogcnin receptors in foll icle membrane preparations of the German cockroach, Blatella germanica', Insect Blochem., 18, 395-404. Korschineck, I., Ziegler, S., Breuss, J, Lang, I., Lorenz, M., Kaun, C., Ambros, P. F., and Binder, B. R. (2001). ' lden rificauon of a novel exon in receptor 2 leading to alternatively spliced mRNAs found in cells of the vascular wall but not in neuronal tissue', J. Biol. Chem., 276, 13 192-13197. Ko7.8rllky, K. F., Call, S. M., Dower, S. K., and Krieger, M. (1988). 'Abnormal intracellular sorting of 0 -linked carbohydrate-deficient interleukin-2 receptors', Mot. Cell. Biol., 8, 3357-3363. Kramer-Guth, A., Quaschning, T., Galle, J., Baumstark, M. W., Koniger, M., Nauck, M., Schollmeyer, P., Marz, W., and Wanner, C. (1997). 'Structural and compositional modifications of diabetic low-density lipoproteins influence their receptor-mediated uptake by hepatocytes', Eur. J. Clin. Invest., 27, 460-468. Kulakosky, P. C., ond Telfer, W. H. ( 1987). 'Selective endocytosis, in vitro, by ovarian follicles from Hyalophora cecropia', Insect Biochem., 17, 845-858. Kulakosky, P. C., and Telfer, W. H. (1990). 'Lipophorin as a yolk precursor in Hyaloplrora cecropia: Uptake kinetics and competition with vitellogenin', Arch. Insect Biochem. Physiol., 14, 269- 285. Kumiawan, N. D., Aliabadizadeh, K., Brereton, I. M., Kroon, P. A., and Smith, R. (2001). ' NMR structure and backbone dynamics of a concatemer of epidermal growth facror homology modules of the human low-density lipoproteia receptor', J. Mot. Biol., 311 , 241-256. Li, A., Sadasivam, M., and Ding, J. L. (2003). ' Receptor-ligand interaction between vitellogenin receptor (VtgR) and vitellogenin (Vtg). implications on low density lipoprotein receptor and /E. The first three ligand-binding repeats of VtgR interacr with the amino­ terminal region of Vrg', J. Biol. Chem .. 278, 2799-2806. Li, Y., Manolo, M. P., van Kerkhof, P., Strous, G. J., and Bu, G. (2000). 'The YXXL motif, but not the two NPXY motifs, serves as the dominanr endocytosis signal for low density lipoprotein receptor-rclared protein', J. Biol. Chem .. 275, 17187-17194. Li, Y., van Kerkhof, P., Marzolo, M. P., Strous, G. J., und Bu, G. (2001a). 'ldentificarion of a major cyclic AMP-dcpendenr prorein kinase A phosphorylarion site within the cytoplasmic tail of the low-density lipoprotcin receptor-related protein: implication for receptor-mediated endocytosis', Mot. Cell. Biol., 21 , 1185-95. Li, Y., Cam, J., and Bu, 0 . (2001b). ' Low-density lipoprotein recepror family: cndocytosis and signal transduction ', Mot. Neurobiol., 23, 53-67. Li, Y., Lu, W., Manolo, M. P., and Bu, G. (2001c). ' Differential functions of members of the low density lipoprotein receptor famil y suggested by their distinct endocytosis rate ', J. Biol. Chem., 276, 18000-18006. Liu, C.-X., Li, Y., Obermoeller-McCormick, L. M., Schwartz, A. L., and Bu, G. (2001). 'The putative rumor suppressor LRPIB, a novel member of the low density lipoprotein (LDL) receptor family, exhibits both overlapping and distinct properties with the LDL receptor-related protein', J. Biol. Chem .. 276, 28889-28896. Loukinova, E., Ranganathan, S., Kuznetsov. S., Gorlatova, N., Migliorin1, M. M., Loukinov, D., Ulery, P. G., Mikhrulenko, I., Lawrence, D. A., and Strickland, D. K. (2002). ' Platelet-derived growth facror (PDGF)-induced tyrosine phosphorylation of the low density lipoprotein receptor-related protein (LRP). Evidence for integrated co-receptor function betwenn LRP and the PDGF. Evidence for integrated co-receptor function between LRP and the PDGF', J. Biol. Chem .. 277' 15499-15506. Mac Lachlan, I., Nimpf, J., and Schneider, W. J. (1994). 'Avian riboflavin binding protein binds 10 lipoprotein receprors in association with vitellogenin', J. Biol. Chem., 269, 24127-24132. 258 REPRODUCTIVE BIOLOGY OF l"lVfRTfBR/\ 11 S

Magranc. J., Rema. M . Pagan. R... Luna, A.• Casaroli-Marnno. R P , A ·Im. B . GAfvels, M., and Vilaro. S (199 ). 'Bovine aonic cndothehal cells e\prcs.• a \'lll •1 of lhe \Cry lo" dcnsuy hpopro1em rccep1or 1ha1 lacks the 0-linkcd sugar domain', J. L.Jpid Res.. 39. 2172-2181 \1agrane, J.. Casaroh-Marano, R. P., Rema. M.. GM\els. M .• and Vilaro.~ (1999) 'The role ofO­ hnked 'ugn~ m detcnmnmg lhc very low densuy hpoprolcin ro:.:cptor stability or release from the cell'. FEBS uu., 451, 56-62. Mahon, M. G, Lmd~tedt, K. A .. Henn:1I1n, M., 'impf, J.. and Schnmlcr, W. J . (1999). 'Muluplc involvement of clu tenn in chicken ovarian follicle development Bmd1ng to two OOC)'1e­ spec1fic mcmbcn of the lo" density lipoprotem receptor gene filnuly', J. 8101. Chem. 274, 4036-4044 Marks, M. S., Ohno, II., K1rchhauser. T., and Bonifacino, J. S. ( 1997) Protein soning by ryrosme- based signals: ndnpting to the Vs and wherefores'. Trendv Cell 81111. 1, 124-128. Marlovll • T. C. Zechme1ster, T., Grucnbcrger, M., Ronachcr, B.. Schw1hla, II., and Blaas, D. (1998a). 'Recombinant soluble low density lipoprotein rcccp1or frugmcnl mh1bi1s minor group rhinovirus infection 111 ''itro'. FASEB J .. 12, 695-703. Mnrlovits, T. C., Abrnhainsbcrg, C., and Blaas, D. (1998b). 'Vcry-low-dcnbllY lipopro1cin recep1or fragmcnl 'hed from HcLa cells inhibits human rhmov1rus mfcc11on' J hrol.. 72, 10246-10250. Mancnsen, P M., Oka, K .. Chris1cn en, L., Re11cnbcrgcr, P. M., Pc1cncn. II H., Chmlen en. A.. Chan, L., Hccgaard, C. W.. and Andreasen, P. A (1997). 'Breast can:moma cpilhchal cells exprc s a \'Cry lo"-dens11y lipoprotein recep1or vanant lad.mg the 0-hnked glyco ylatlon domain encoded by exon 16, but w11h full bmdmg ac11v11y for \Crine proteinase serpm complc~e<> and Mr-40,000 rcceptor-assoc1a1ed protein', E11r. J Bwcltem., 2~8. 583-591. Mal)'ash, V. Geier. C. Hcnske, A.. Mukherjee. S.. Hush, D.. Tb1clc. C. Grant, B , Maxfield, F. It. and Kurzchaha. T V. (2001). ·Distribution and trun pon of choJc,1erol m Cae11orhabd1t1S elega1u', Mo/ 8101 Cl?ll, 12, 1725-1736. Ma)'cr, U. N1scht, R.. Poschl. E.. Mann, K.. Fukuda, K.. Gerl. M .. Yamada. Y. and T1mpf. R. (1993). 'A single fGF-hkc motif of lammm IS responsible for high affiniiy nidogcn bmdmg'. EM80 J, 12, 1879-1885. Mayhew, M., Handford, P.. Baron. M., Tse, A. G., Campbell, I. 0., ond Brownlee, G. G. (1992). 'Ligand requirement for Cal+ binding to EGF-like domain ', Protf:in Eng .. S, 489-494. Mellmon, I .. Fuchs, R .. and llclenius, A. (1986). •Acid1fic111ion of the cndocyt1c and exocyuc pa1hwuys', A111111. Rel'. Biochem .. SS, 663-700. Mikha1lenko, I , Considine, W., Argraves. K. M., Loukinov, D, Hyman, B. T., and Strickland, D. K. ( 1999). 'Functional domains of the very low density lipopro1c1n rcccp1or: molcculnr analysis of ligand binding and ac1d-dcpcnden1 ligand dissocrnuon mcchan1>ms', J Cl?ll Sci, 112, 3269- 3281. M1kha1lenko. 1., Battey. F D., M1ghonni. M.. Ruiz. J F, Argraves, K., Moayen. M. and Stnck land.

D K. (2001). ' Rc:cogn111on of a 2 -macroglobulm by 1hc low den;1ty hpopro1ein receptor­ rela1ed protein requires the coopcrauon of t"'o ligand bmdmg clu,1er regions', J. 810/ Chem.. 276, 39484.-39491 Miller. W E., Maudslcy, S, Ahn. S . Khan. K. D.. Luttrell. L M , and LcO..ow11L. R. J. (2000). ·~anc.un I intcracb "1th the caralyuc domain of the l)ll'O,mc lona o;c c-SRC Role of belll­ a.rrc 11nl-dcpcnden1 targeting of c-SRC in receptor cndocy10 1s', J 8101 Chem. 275, 11312- 11319 Moc,tn1p, S K (1994). 'The ~-macroglobulin rcccplor and epithelial glycoproicm-330: two giant receptor. mcd1a11ng cndocyt~1s of muluplc hg;mds', Bux/11111 Biaph.r, ktu 11 97. 197-213 Morash, B. A., Tan. M. II , assar. B. A.. Too. C. K.. and Guernsey. D L. ( 1998) •A novel mutation m bon 4 of lhc low dcnslly hpopro1cm rccep1or gene re'uhmg m heterozygous familial hypcrcholc tcrolcm10 a socrnled with decrea~cd ligand bmdm1f, Arhcrordcros/v, 136, 9-16. Mullbcrg, J., Rauch, C I .. Wolfson. M F.. Castner, B., F1t7ner, J . Olien Lvan., C .. Mohler, K. M.. Co,man. D. and Black, R. A. (1997). 'Funhcr evidence for a common mechanism for \hcddmg of cell surface pro1cins,' FEBS Lei/., 40 I, 235-2311 r SECT VrTELLOGENINIYOLK PROTElN RECEPTORS 259

~IMmura, Y. . Yamamoto, M., and Kumarnaru. E. (1998). 'A variant very low density lipoprotein receptor lacking 84 base pairs of 0-linked sugar domain in the human brain myelin ', Brain Res., 793, 47-53. Nimpf, J., and Schneider, W. J. (1 998). 'The VLDL receptor: an LDL receptor relative with eight ligand binding repents, LR8', . 141, 191-202. ~ impf. J., Stifaru, S., Bilous, P T . and Schneider, W. J. (1994). ' The somatic cell-specific LDL receptor-related prolCln of the chicken· close kinship to mammalian LDL receptor gene family members', J Biol Chem , 269, 212-219. Sonh. C. L., and Blacklow, S C. ( 1999). 'Structural independence of hgand-bindmg modules five and six of the LDL receptor'. Biochemistry, 38, 3926-3935. ~onh . C. L., and Blacklow, S. C. (2000). 'Solution structure of the sixth LDL-A module of the LDL receptor', Biochemis1ry. 39, 2564-257 1. N)' kJaer, A., and Willnow, T. E. (2002). 'The low-density lipoprotein receptor gene family: a cellular Swiss army knife?', Trends Cell Biol., 12, 273-280. Ohno, H., Stewan, J., Fournier, M C., Bos hart, H , Rhee, I., Miyatake, S., Saito, T., Gallusser, A., Kirchbausen, T .• and Bomfacmo. J. S. (1995). 'Interaction of tyrosine-based sonmg signals with clathrin-nssociated protems'. Science. 269, 1872-1875. Okabayashi. K., Shoji, II., akamura, T., Hashimoto, 0 ., Asashim~ M ., and Sugino, H (1996). 'cD A cloning and expres ion of the Xt nopus /oevif vitellogenin :i:ccptor', B1ochem. Biophys, Res. Comm., 224, 406-413 O:;ir, E. 0 ., and Law, J. II. (1986). 'Studies on bmdmg and uptake of vitellogenin by follicles of the tobacco homworm, Manduca sex1a', Arclr. /11secr Bloc/rem. Physiol., J, 513-528. Prat, F., Coward, K., Sumpter, J. P. • and Tyler, C. R. ( 1998). ' Molecular characterization and expression of two ovarian hpoprotein receptors in the rainbow trout, OncorlryncJ111s mykiss', Biol. Reprod., S8, 1146- 1153 Quinn, K. A., Grimsley. P G., Dai, Y P., Tapncr, M., Chesterman, C. .• and Owen by, D. A. (1997). ' Soluble low den ny hpoprotem receptor-related protein (LRP) circulates m human plasma', J. Biol. Chem , 272, 23946-52391 . RafTnT, R., Vulcrmrica, J .• We1sgraber, K. H.. Rassan, E., lnnerarity, T. L., nnd Milne, R. (1999). ' Bacterial expression and purification of the Fab fragment of a monoclonal anubody specific for the low-density lipoprotein receptor-binding site of human apolipoprotein E', Protein E.xpr. Purif., 16, 84-90. Ranganathan, S., Knaak. C., Moroles. C. R., and Argraves, W. S. ( 1999). 'ldentificauon of low density lipoprotein receptor-related protein-2/megalin as an endocytic receptor for seminal vesicle secretory protein II', J Biol Chem.. 274, 5557-5563. Ra1khcl. A. S. (1984). 'The accumulative pathway of vitcllogenm in the mosquito oocyte; a high resolution immuno- and cytochemical rudy', J Ultrastroct Res.. 87, 285-302. Ra1khcl, A.S., and Lea. AO (1985) '-mediated formation of the endocyuc complex in mosquuo oocytcs', Gen Comp. Endocrinol SJ, 424-435. Ra1khel, A. S., and Ohadialln, T. S. ( 1992). ·Accumulation of yolk proteins m insect oocytes', Annu. Rev. Emomol., 37, 217-25 I. Recs, 0 . J. G., Jones, I. M., Handford, P. A., Walter, S. J., Esnouf, M. P., Smith, K. J., and Brownlee, G. G. (1988). 'The role of J}-hydroxyaspanate and adjacent catboxylate re idues in the fi rst EGF domain of human factor IX', EMBO J . 7, 2053-2061. Rettenbergcr, P. M.• Oka. K., Ellgaard, L., Petersen, H. II , Chnstensen, A., Martensen, P. M. • Monard, D. . Etzerodt, M.• Chan, L.. and Andreasen. P A (1999). ' Ligand bmdmg propen1es of the very low density l1poprotcm receptor. Ab:.ence of the Ihm! complement-type repeat encoded by exon 4 is associated with reduced binding of Mr 40,000 receptor-associated protein', J. Biol. Chem . 274, 8973-8980. Richard, 0 . S., Gilben, M., Crum, B., Hollinshead, D. M., Scheible, S., and Scheswohl. D. (2001). 'Yolk protein endocytosis by oocytes in Drosnphila melanogas1er: immunonuorescent localization of clathrin, adaptin and the yolk protein receptor', J lme('I Plry.riol .. 47, 7 15-723. 260 REPRODUCTIVE BIOLOGY OF INVERTEBRATES

Rodenburg, K. W., KJoller. L., Petersen, H. H., and Andreasen, P A. (11198). ' Binding ofurolunase­ type plasminogen ac11vator-plasminogen activator mh1b11or- I c mplex to the cndocytos1s receptors ~ -macroglobulin receptor1ow-dcnsiry lipoprotcm ~'to >r-related protein and very­ low-den 1ry lipoprotem receptor involves baste re 1duc in the 1 1h1bttor', Biochem. J., 329, 55-63. ROhrlcasten, A., and Ferenz, H.-J. (1985). 'In vuro-study of the selective endocytosis of vnellogenin by locust oocytes', Wilhelm Roux's Arch.. 195, 411-416. ROhrlcasten, A., and Ferenz, H.-J. (1987). 'Inhibition of yolk fonnat1on m locust oocytes by trypan blue and suramm', Wilhelm Roux Arch. Dev. Biol.• 196, 165-168 ROhrkasten, A., and Ferenz, 1-1.-J. (1992). ' Role of the lysine and arginine residues of vitellogenin in high affinity binding to vitellogenin receptors in locust oocyte membranes', Biochim. Biophys. Acta .. 11 33, 160-166. ROhrkasten, A., Ferenz, H.-J., Buschmann-Gebhardt, B., and llafer, J. (1989). ' Isolation of the vitellogenin-binding protein from locust ovaries', Archlv. Insect Biochem. Phys/of.. 10, 141- 149. Rong, L., Gendron, K., Strohl, B., Shenoy, R., Wool-Lewis, R. J , and Bates, P. (1998). 'Characterization of detenninants for envelope binding and infection 1n tva, the subgroup A avian sarcoma and lcukosis virus receptor', J. Viral., 12, 4552-4559 Roth, T F., Cutting, J . A., and Atlas, S. B. (1976). 'Protein tran port a elective membrane mechamsm', J. Supramol. Struct. . 4, 527-548. Rudenko, G., Henry, L., Henderson, K., lchtchenko, K., Brown, M S .. Gold tein, J. L .. and Dciscnhofer, J. (2002). 'Structure of the LDL receptor ei1rraccllular domain at endosomal pH', Science, 298, 2353-2358. Runova, 0 . L., Mandclshtam. M. J., Golubkov, V. I., Sukonina, V. E .• Dcniscnko. A. D., and Ga1tskhok1, V. S. ( 1997). 'Expression of cDNA fragment encoding hgand-binding dom81D of human low densiry hpoprotein receptor m Escherichia coli cells', Biochemistry (Moscow). 62, 1037-1045. Russell, D. W .. Brown, M. S., and Goldstein, J. L. (1989). 'Different combmations of cysteinc-rich repeats mediate binding of low densiry lipoproiein receptor to two dtlTerent proteins', J. Biol. Chem .. 264, 2 1682-21688. · Russell, D. W., Schneider, W. J., Yamamoto, T., Luskey, K. L., Brown, M. S., and Goldstein, J. L. ( 1984) ' Domain map of the LDL receptor: sequence homology with 1he cpidennal groW1h factor precursor', Cell, 37, 577-585. Saha, S., Boyd, J., Werner, J. M. . Knon, V., Handford, P. A., Campbell, I. D., and Downing. A. K. (2001). 'Solution tructure of the LDL receptor EGF-AB pair: a paradigm for the assembly of tandem calcium binding EGF domains', Structure, 9, 451-456. Salcthwel, R., Zhang, J. C., Stnckland, D. K., GAfvcls, M , and McCrae, K R. (2001). ' Regulation of the hgand bindmg activ1ry of the human very low dens1ry hpoprotcm rcccplor by protein kmase C-dcpcndent phosphorylation', J. Biol. Chem , 276, 555-562 Sttndoval, I. V., and Bakke, 0 . (1994). 'Targeting of membrane protems to endosomes and lysosomes', Trem:b Cell Biol. 4, 292-297. Sappmg1on, T W (2002). 'The major yolk protems of higher D1p1ct11 are homologs of a class of mmor yolk protem m Lcp1doptcra', J Malec. Ew>I . SS, 470-475. Sappmgton, T W , and Ra1khel, A. S (1995). ' Recep1or-mcd1a1cd cndoc)'l~•s of yolk protems by msect ooeyte:.', m Recent Atll:ances in Insect B1ochem1Stry anti Molecular Biology (Eds. E. Ohn1sh1, II Sonobe, and S Y Takahashi), Un1ver..11y of Nagoya Pre s, Nagoya, Japan, pp. 235-257 Sappmgton, T. W., and IU1khel, A. S. (1998a). ' L1gand-bmdmg domams in vuellogcnin recep1ors and other LDL-rcccptor fa mily members share a common ancestral ordering of cys1eine-rich repeats', J Molet: El-of.. 46, 476-487 Sapp1ng1on, T. W., ond Ra1khcl, A. S. (1998b). 'Molecular characteristics of insect vi1ellogenins and vucllogcnm receptors'. Insect Blocltem Molec Biol.. 28, 277-300. INSECT VITELLOGENI 'YOLK PROTEIN RECEPTORS 261 app1ng1on. T W Ila ·s A p . punfi · ·• >' • and Ra1khel, A S ( 1995). 'Mo qu110 \ 11ellogenin receptor· 0 25• ~~~· ~7 de,clopmeniaJ and biochcm1cal charac1enzat1on', Insect 81ochnn Molec Biol appmgton, T. W Kok V A Cho . of the • . oza. · ·• • W.-L, and Raikhel, A. S (1996). 'Molecular cbaracterizauon . lk mosquuo vllellogenin recep1or reveals une~pcctcd high homology to the Drosophtlo 0 > protein receptor' Proc. Natl Acod. Sci. USA 93 8934-8939 Sapping1on T w o h . • ' · • .. is 1, K. and Ratkhel, A. S. (2002). ·s1ructural charac1eris11cs of insecl v1 tc Ilogcn • · R m V' in • 1? eproducuve Biology of lnvertehrote:,, Volume XII Port A - Recent Progress uellogen~is .

Stnckland. D. K . Gonias, S. L., and Argra~es. W. S. (2002). 'D1~er>c role for the LDL receptor family', Trends Endocrm Metab., 13, 66-74 SOdhof, T C, Gold tem, J. L., Brown, M. S., and Russel, D W (198.S). 'The LDL receptor gene; a mosaic of exons shared with different proteins', Sc1enu. 228, 81.S- 22. Sun, J, Hiraoka, T., Ommcr, . T., Cho, K.-H., and Riukhel. A (~000). 'Lipophonn as a yolk protein in the mosqu110, Aedes oeg>pti ·. Ins. Biochem Mo/ Bio JO, 1161-1171. Sun. X.-M., and Souter, A. K. (1999). 'Expression in vitro of oltemauvely pliced variants of the messenger RNA for human apolipoprotein E receptor-2 1den111icd 1n human ussues by nbonuclease protection assays·, Eur. J. Biochem , 262, 230-239 Suzuki. T., and Riggs. A. F. (1993). ' Linker chain LI of earthwonn haemoglobin: structure of gene and protein: homology with low density lipoprotein receptor', J. Biol. Chem., 268, 13548· 13555. Takeda, T., Yamazaki. H., and Farquhar, M. G. (2003). ' ldentificallon of an apical sorting determinant in the cytoplasmic roil of megalin', Am. J. Phys/of. Cell Physiol., 284, Cl 105-CI 113. Tan, P K., Howard, J. P., and Payne, G. S. (1996). 'The sequence NPFXD defines a new class of endocytosis signal in Saccharomyces cerevisiae', J. Cell Biol.. 135, 1789-1800. Telfer, W. H (2002). ' Insect yolk proteins: a progress report', 1n Reproductive Biology of lm'f!rtehrotes. Volume XII Part A - Recent Progress In Vitellogenesis. (Volume Eds. A. S. Ra1khel and T. W. Sappington; Series Eds. K.G. Ad1yodi and R.G. Ad1yodi). Science Pubh hers, Enfield, USA, pp. 29-67. Telfer, W H, Huebner. E., and Smith, S. D. (1982). 'The cell biology of v11ellogenic follicles in Hralophora and Rhodnius'. in Insect Ultrastructure. (Eds. R. C Kmg and II. Akai). Plenum, NY. pp. 118-149. Tom11a, Y .. Kim, D. H. . Magoori. K.., Fujino, T., and Yamamoto, T. T (1998). 'A no..,el lo\\-density lipoprotem receptor-related protein with type fl membrane protem-hke structure is abundant m heart', J B1ochem., 124, 784-789. Tonelli, M., Peters, R. J., James, T. L., and Agard, D. A. (2001). 'The soluuon structure of the viral binding domain of Tva, the cellular receptor for subgroup A avian lcukosis and sarcoma virus', FEBS Leu .. 509, 161-168. Trowbridge, I. S., Collawn, J. F., and Hopkins, C. R. (1993). 'Signal-dependent membrane-protein trafficking in the endocytic pathway', Annu. Rev. Cell Biol. 9, 129- 161. Tsuchida, K., and Wells, M. A. (1990). ' Isolation and charac1eri1ation ofa lipoprotein recepior from the fol body of an insect, Manduca sexto', J. Biol. Chem .. 265, 5761-5767. Ullman, C. G., Haris, P. I., Smith, K. F., Sim, R. B., Emery, V. C., and Perkin~ . S. J. (1995). ·~­ Sheet secondary structure of an LDL receptor domain from complement factor I by consensus structure predictions and spectroscopy', FEBS Leu.. 371, 199-203. van Antwerpcn, R.. Conway, R.. and Law, J. H. (1993). 'Protein and hpoprotcm uptake by developing oocytcs of the ha\\ kmoth, Manduca sexta: An ultra tructurnl and immunocytochemical study', Tissue Cell, 25. 20.S-218 van der Horst, D. J., \'&n lloof, D., van Marrewijk, W. J .. and Rodenburg, K. W. (2002). 'Alternative hp1d mob1liz.auon: the insect shuttJe system', Mo/ Cell B10c hem , 239, 113-119. van der We thuyzen, D. R., Stein, M L., Henderson, H. E., Mon11 , A D.. Founc, A. M • and Coetzee. G A (1991) ' Delcuoo of two growth-factor repeats from the lo"'-dcns1ty-hpoprotem receptor 1cceleratc us degradation', B1ochem. J .. 278, 677-682 van Oriel, I R., Davi • C G.• Goldste10, J. L., and Brown, M. S (19 7) 'Self-assoc1at1on of the low den lly hpoprotcm receptor mediated by the cytoplasmic domain', J Biol Chem., 262, 16127-16134. van lloof, D., Rodenburg, K. W., and van der Horst, D. J (2002). 'In cct hpoprotcin follows a tmn fcrrin -hkc recycling pathway that is mediated by the insect LDL receptor homologue', J Cell Sci, 115, 4001-4012. Vash, B., Phung, N., Zcm, S., and DeCamp. D. (1998). 'Three complement-type repents of the low­ dcnsity lipoprotcin receptor-related protein define o common bmdmg site for RAP, PAI-I. and lactofemn', Blood, 92, 3277-3285. INSECT JTELLOGENfN/YOLK PROTEIN RECEPTORS 263

Vassiliou, G. ( 1997). 'Pharmacological concentrations of suramin inhibit the binding of

a2 -macroglobulm to its cell-surface receptor'. Eur. J. Biochem., 2SO, 320-325. Warrier, S., and Subramoniam. T. (2002). 'Receptor mediated yolk protein uptake in the crab Scylla serrata: crustacean ' uellogenin receptor recognizes related mammalian serum lipoproteins', Mal. Reprod. Dev. 61, 536-548. Warshawsky, I., Bu, G., and Schwartz, A. L. (1995). 'Site within the 39-k.Da protein important for regulating ligand binding to the low-density lipoprotein receptor-related protein', Biochemistry, 34, 3404-3415. Wilde, A., Beattie, E. C., Lem, L., Riethof, D. A., Liu, S. H., Mobley, W.C., Soriano, P., and Brodsky. F. M. (1999). 'EGF receptor signaling stimulates SRC kinase phosphorylation of clathrin, influencing clathrin redistribution and EGF uptake,' Cell, 96, 677-87. Willnow, T. E. (1999). 'The low-density lipoprotein receptor gene family: multiple roles in lipid metabolism', J. Mo/. Med.. 77, 306-315. Wilson, C., Wardell, M. R., Weisgraber, K. H., Mahley, R. W. , and Agard, D. A. (1991). 'Three­ dimensional structure of the LDL receptor-binding domain of human apolipoprotein E', Science, 2S2, 18 17-1822. Yamamoto, T., Davis, C. G., Brown, M. S., Schneider, W. J., Casey, M. L., Goldstein, J. L., and Russell, D. W. (1984). 'The human LDL receptor: a cysteine-rich protein with multiple Alu sequences in its mRNA', Cell, 39, 27-38. Ziak, M., Kerjaschki, D., Farquhar, M. G., and Roth, J. (1999). 'ldentHication of megalin as the

sole rat kidney sialoglycoprotein containing poly a2 ,8 deaminoneuraminic acid', J. Am. Soc. Nephrol., 10, 203-209. Zingler, K., Belanger, c., Peters, R., Agard, D., and Young, J. A. T. (1995). 'Identification and characterization of the viral interaction determinant of the subgroup A avian leukosis virus receptor', J. Viral., 69, 4261-4266.