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1* j

it * * The Mouse Gene Ptprf Encoding the Leukocyte Common Antigen-Related Molecule LAR: Cloning, Characterization, and Chromosomal Localization

R o e l Q. J. S c h a a p v e ld , A r n M. J. M. van den Maagdenberg, Jan T. G. Schepens, Daniël Olde Weghuis,* Ad Geurts van Kessel,* Bé Wieringa, and W iuan J. A . J. H e n d rik s 1

Departments o f Cell Biology and Histology and * Human Genetics., University o f Nijmegen, The Netherfands

Received October 24, 1994; accepted February 16, 1995

of protein tyrosine kinases (PTKs) in these processes The human receptor-like protein tyrosine phospha­ and the induction of their activity have been exten­ tase leukocyte common antigen-related molecule sively studied, but the recent identification and charac­ (LAR; gene symbol PTPRF) closely resembles cell ad­ terization of many protein tyrosine phosphatases hesion molecules, which suggests that it may be in­ (PTPases) suggest that dephosphorylation of signal volved in the regulation of phosphotyrosine levels transduction proteins is also a crucial event in signal through cell-cell or cell-matrix interactions. To ob­ transduction (Fischer et al.} 1991; Brady-Kalnay and tain a better understanding of LAR function, we have Tonks, 1994). To date more than 30 PTPases have been characterized the mouse gene as a first step to­ Ptprf identified (Mourey and Dixon, 1994). Sequence compar­ ward site-directed mutagenesis studies and in vitro in isons have revealed that there are two major classes of vivo. The cytoplasmic region of the mouse LAR (mLAR) protein is encoded by 11 exons that span only 4*5 kb PTPases (for review see Tonks et ah, 1992; Mourey and of genomic DNA. Compared to the known exon-intron Dixon, 1994), namely (i) those found in the cytoplasm structures of other mammalian receptor-like protein or nucleus that contain only one tyrosine phospha­ tyrosine phosphatase genes, such as Ptpra (encoding tase domain and (ii) membrane-bound, receptor-like LRP) and Ptprc (coding for Ly-5), the Ptprf gene part PTPases (RPTPases) that have two tandemly repeated encoding the cytoplasmic region of mLAR contains not catalytic domains. There also exist intermediate forms only smaller, but also fewer introns. Sequence analysis such as HPTP/3 (Krueger et al.3 1990) and PTP-SL of both phosphatase domains of mLAR and, its homo­ (Hendriks et aL, 1995) that are transmembrane pro­ logs MPTP6 and mRPTPcr revealed a higher evolution­ teins with only one catalytic domain. ary conservation of the second, C-terminal domain in The RPTPases can be subdivided into five types comparison to the first domain. Fluorescence in situ based on the structure of their extracellular segments hybridization was used to map the Ptprf gene to region (Mourey and Dixon, 1994). Type I represents the CD45 C6-D1 on mouse chromosome 4. © 1995 Academic Press, Inc, family, which comprises multiple isoforms arising from differential splicing of the RNA of a single gene. Type II members (e.g., LAR, HPTP<5, RPTPcx, RPTPfi, and INTRODUCTION RPTP/c) are characterized by the presence of multiple immunoglobulin (Ig) and fibronectin (FN) type Ill-like Protein tyrosine phosphorylation is recognized as an domains. Type III members carry multiple FN-III do­ important reversible reaction controlling many aspects mains (e.g., HPTP/?), while type IV members (e.g., of cellular function, including growth and differentia­ HPTPa and HPTPe) possess small glycosylated seg­ tion, cell cycle control, and cytoskeletal integrity ments. Finally, type V members (e.g., HPTP£ and (Tonks et al.} 1992; Mourey and Dixon, 1994). The role HPTPy) have an amino-terminal motif with homology to carbonic anhydrase. Sequence data from this article have been deposited with the EMBL/GenBank Data Libraries under Accession Nos.: mLAR The extracellular region of the type II RPTPases re­ (Z37988), rLAR (M60103), hLAR (Y00815), mPTP6 (D13905), hPTPS sembles that of cell adhesion molecules (CAMs) such (X54133), mRPTPtr (D28530), rPTPa (A49104), and hRPTPo- as N-CAM (Edelman and Crossin, 1991). Recently, ho- (S78080) mophilic adhesive properties have been attributed to 1 To whom correspondence should be addressed at the Department of Cell Biology and Histology, University of Nijmegen, P.O. Box 9101, RPTPfi and RPTPk (Gebbink et a l s 1993; Brady-Kal­ 6500 HB Nijmegen, The Netherlands, Telephone: +31 80 614334. nay et a i 3 1993; Sap et al.y 1994). In combining cell Fax: +31 80 540525. adhesion motifs at the cell surface with intracellular

124 0888-7543795 $6.00 Copyright © 1995 by Academic Press, Inc. A ll rights of reproduction in any form reserved. MOUSE Ptprf GENE STRUCTURE 125

A al., 1988), thePipr/gene exhibits a more compact struc­ #11 ture. #5 Comparison of both phosphatase domains of mLAR E E E 5' with closely homologous sequences of MPTP6 (Mizuno T r r et al., 1993) and mRPTPa (Ogata et aL, 1994) revealed A kb B B B H BB B H H B B B a higher evolutionary conservation of the second, C- terminal domain compared to the proximal “catalyti- B cally active” domain. 129 Plprf locus Sstl H E HE B Bglll Finally, we report the chromosomal localization of

-Lt/ / F r - r - t t h i J - / } [r , /-} J-J J > J J zhzr r zzz :r¿ rz r i ¿.j-¿ u ,z the P tprf gene to region C6-D1 of mouse chromo­ 1 kb 1 some 4. i r PO RSTUVWXY 1 MATERIALS AND METHODS 11 HHpHti| h 3’ UTR cys cys Isolation of mouse LAR genomic and cDNA clones. Cosmid clones FIG. 1 . Schematic representation of the Ptprf locus (A) and exon- were isolated from a mouse 129/SvEv genomic DNA cosmid library infcron structure of the region of the gene encoding the phosphatase (kindly provided by Dr. M. Hofker, University of Leiden, Leiden) domains of the mLAR protein (B). (A) Thick solid bars indicate the using a random-primed (Feinberg and Vogelstein, 1983) 1.5-kb positions of the cosmid clones relative to the Ptprf locus. A hatched -EcoRI-Sa/I human LAR (hLAR) cDNA fragment (positions 4444- bar marks the S stl- B g lll fragment that is shown in more detail in 5933, Streuli et a l, 1988) as a probe, Hybridizations were carried B. B, £am H I;E, ÆcoRI;H, H indlll, (B) Introns (thin lines) and exons out according to Church and Gilbert (1984), and filters were washed (filled boxes) are drawn to scale. Exons are numbered P thru Z. for 5, 10, and 30 min at 65QC in 0.25 M sodium phosphate/1 % SDS/ The regions encoding the two phosphatase domains are indicated by 1 mM EDTA. Positive clones were purified by subsequent rounds of brackets and numbered 1 and 2, respectively, Cys indicates the posi­ low-density screening. tion of the codon for the conserved cysteine residue w it h in the signa­ The same hLAR cDNA probe was used to screen an oligo(dT)- ture sequence of each phosphatase domain. 3' UTR, 3 ' untranslated primed mouse brain cDNA library in Lambda ZAPII (Stratagene). region. Filters were washed three times for 30 min at 65°C in 2 X SSC/0,2% SDS. Positive phages were plaque-purified, and inserts were rescued as pBluescript SK plasmids according to the manufacturer’s protocol, phosphatase activity, these RPTPases may be involved Sequence analysis. Nested deletion mutants of cDNA clqne in the control of cell growth, motility, and differentia­ mLAR#9 were generated using Exonuclease III (Promega), and nu­ tion in a direct response to cell-cell interaction. cleotide sequences were determined using the double-stranded DNA dideoxy sequencing method (Hattori and Sakaki, 1986). A 6 .5-kb The cytoplasmic region of most type II RPTPases Satl-BarnlH Ptprf genomic fragment was used for exon—intron de­ contains two tandem phosphatase domains of approxi­ termination according to the shotgun sequencing strategy of Deinin- mately 260 amino acid residues each, but it is not clear ger (1983). Briefly, fragments of around 500 bp were generated by at present whether both domains are enzymatically ac­ sonication, biunt-ended using Klenow (Boehringer), and subcloned into the Sm al site of vector pGEM4 (Promega). Clones, grown in tive in vivo or exhibit different substrate specificities. microtiter plates, were replica plated onto nitrocellulose filters and Structure-function relationships have been estab­ screened with the mLAR cDNA#9 insert. Thirty positive clones were lished only for phosphatase domains expressed in bac­ used for sequence determination (Hattori and Sakaki, 1986). DNA teria and therefore outside their natural context. Al­ sequence gel readings were recorded, compared, edited, and assem­ bled using the IGSUITE 5.35 package (Intelligenetics Inc., Moutain though site-directed mutagenesis studies have shown View, CA). Sequences were aligned using the GCG Wisconsin pro­ the significance of the “signature sequence" (I/V)HCX- grams PILEUP and LINEUP (Devereux et a l, 1984). Evolutionary AGXXR(S/T)G for tyrosine phosphatase activity of the reconstruction was performed using the program FITCH supplied first, transmembrane proximal phosphatase domain in the phylogeny inference package PHYLIP (distributed by Dr. J. Felsenstein, University of Washington, Seattle). FITCH uses dis­ (Mourey and Dixon, 1994), it remains to be determined tance matrices to construct trees without allowing negative branch whether the distal phosphatase domain also exhibits length (Fitch and Margoliash, 1967). catalytic activity (Wang and Pallen, 1991; Tan et aL, Fluorescence in situ hybridization. Fluorescence in situ hybrid­ 1993) or plays only a regulatory role in modulating the ization was performed on mouse strain 129-derived E14 embryonic activity of the first domain (Streuli et al., 1990; Pot et stem cell (Handyside et a l, 1989) metaphase spreads for the regional localization of the Ptprf gene, using mouse cosmid 5 as a probe. aL, 1991; Krueger and Saito, 1992). However, in vitro Biotinylated cosmid DNA was dissolved in 10 pi hybridization solu­ studies are inadequate to address such questions be­ tion containing 2x SSC, 1 0 % dextran sulfate, 1% Tween-20, and 50% cause specific inhibitors of PTPases are not yet at hand formamide. The probe mixture was he at-denatured at 80°C for 10 and substrates and ligands are unknown. min, followed by incubation at 37°C to allow reannealing of highly repetitive sequences. Hybridization of this probe to heat-denatured To initiate studies of the role of LAR domains in an chromosome spreads, under a cover slip, was carried out overnight at organismal context, we set out to isolate structural and 37°C. Hybridizing probe was detected immunohis to chemically using genomic mouse LAR (mLAR) DNAs. Here we describe fluorescein isothiocyanate conjugated to avidin-D (Suijkerbuijk et al., the organization of the Ptprf gene region encoding the 1991). Images of metaphase prepar ations were captured by a cooled high-performance CCD camera (Photometries) coupled to a Macin­ cytoplasmic part of mLAR. Compared with known tosh II computer. Separate images of both mLAR hybridizing signals exon-intron structures of other mouse PTPase genes, and DAPI-counterstained chromosomes were transformed into pseu­ such as Ptpra (Wong et aL, 1993) and Ptprc (Saga et docolored images using image analysis software. 1 2 6 SCHAAPVELD ET AL. \

... AT G CGA GAC CAC CCG CCC ATC 21 K R D H P P I (1306)

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TAT GTG TTC ATC CAC GAG GCC CTG CTA GAG GCT 846 R N K Y V F 1 H E A l l E A (1581)

GCC CAC ATC CAG AAG CTA GGC CAA GTG CCT CCC 921 H H N L Y A H 1 Q K L G Q V P P (1606) lExon U GCC AAC TCC AAG GCC CAC ACG TCG CGC TTT GTC 996 H A N S K A H T S R F V (1631)

AAC ATC ATG CCC TAT GAG CTG ACC CGA GTG TGC 1071 N N F N N I M p Y E L T R V C (1656) iËxon V GCC AGC TTT CTA GAT GGC TAC AGA CAG CAG AAG 1146 L 1 1 N A S F L D G Y R Q O K (1681)

•'•"i ' i ST îV V iV « V c V « > GAC TTC TGG CGC ATG TTA TGG GAG mm 1221 m* v . S * IP I A D F W R H L U E n s (1706) jExon W 5;ÇQÛ M f i f i ® S m â wSwvvi» ï i t e pH 1296 C H Y U P A t R (1731)

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CGC ATG CGC TAT GAG GGT GTG GTT GAC AT G TTC CAG ACC GTG AAG ACC CTC CGC ACA CAG CGC CCT GCA ATG GTG 1671 RMRYEGVVDHFÛTVKT LRTQRPAMV (1856) l£xon Z CAG ACA GAG GAC CAA TAC CAG CTG TGC TAC CGT GCG GCC CTG GAA TAC CTC GGC AGC TTT GAT CAC TAT GCA ACG 1746 QTEDOYQLCYRAALEYLGSFDHYAT (1881) TAA* CTACTGCTCCCCTCTCCTCCGACGCTCCCCCGCGGCTCCGGAGGGACCCAGCTCCTCTGACCCATACCAACCATCGTCCAGCCCTCCTGCACGGA 1844

TGCTGTTGCCGGCAGAGCACAGCCCACTGGGATCACAGCATTTCGGGGAACATTGCCACACCAGTCAGAGAGCCCAGAACACCTGGGCAAGTAGGCGGA 1943 CTGGCAGCCTGGCTCTGGGCCCTCGTCCACCGGGCCAAÙTGGAGCCCCGCTTCAAGCTCrCTGTTCAGCTCCGCGTTCTCATGCTTCTCATGGGGTGGG 2042 AAAAGGGGGCAAAGCCCCCACTTTTTATACACTAGGCGGGGTAGACTGCGGGGTCCTAGCCTCTrcCTCCGACTTTGCTTTTGCAGGTCTTTCACTGCA 2141 GATGGGGCTGCTGTGGGAGTTGGGACT7GTTTGTTTTCCTTTTTGAGTTCACGTTGGATCC... 2202 FIG. 2. Definition of the exon-intron boundaries within the partial inLAR cDNA sequence. Exon-intron boundaries are indicated by arrows at the first nucleotide of each exon. The 3' UTR sequence is given up to the jBamHI site as indicated in Fig. 1 . Numbers to the right indicate nucleotides as present in clone mLAR#9 and, in parentheses, amino acids according to the numbering system of Streuli et aL (1988). Regions that exhibit 100% identity with previously published PCR-derived mLAR fragments (Hendriks et a l, 1995) are shown on a gray background. Underlined sequences indicate the “active site” signature motif.

RESULTS AND DISCUSSION mains in the LAR signal transduction pathway using reverse genetic approaches. As a first step we isolated Isolation and Characterization of the mLAR- and characterized mouse LAR genomic and cDNA Encoding Ptprf Gene clones, with special emphasis on the region encoding We are currently investigating the biological role of the phosphatase domains. LAR and the functions of the tyrosine phosphatase do» A 1.5-kb ÆcoRI-SaZI hLAR cDNA probe encoding MOUSE P tp rf GENE STRUCTURE 127

i H I 1 I as shown in Fig. 1. We assume that the other, more

LRP ¡<3- y : j 1 weakly hybridizing cosmid clones contained either 3 'UTR P tprf pseudogenes or genes with homology to P tprf / / / / / / / rS/if * \ y?x 7 • ^ -, • • r y'.WÏL^r' r>T7 such as Ptprd (encoding MPTP<5, Mizuno et ah, 1993) % W1' ■ 1 y-.- [ a Ly-5 \2S&11* » 'v* ' Ô6'1>'■ -’Vfim i &tsVrv •/i f&rSi'133’ : : i vy'** l.ièi • ' ’-V6iV»W?r 4* - v S B 3' UTR or Ptprs (coding for mRPTPcr, Ogata et a l 1994). j •t / -} " * 1 1 , i V 7>^ * fr We compared genomic and cDNA sequences to posi­ « tion exon-intron boundaries within the Ftp rf gene. To mLAR l[ ^ ,.S’' " ' V>V.r., ! : j / * n s ir 3' UTR this end, 10 cDNA clones were isolated from a Lambda r ZAPII mouse brain cDNA library using the hLAR Domain 1 Domain 2 cDNA probe mentioned above. End-in sequencing and FIG. 3* Comparison of exon segmentation as observed in the comparison with the cognate positions in hLAR (Streuli Ptpra, Ptprc, and Ptprf genes within the region encoding the phos­ et a l 1988), rat LAR (rLAR, Pot et ah, 1991), and frag­ phatase domains of RPTPases LRP (Wong et al., 1993), Ly-5 (Saga ments of mLAR (Hendriks et al. , 1995) revealed that et al., 1988), and mLAR, respectively. Dashed lines indicate identical boundaries. Downward arrows indicate introns present in Ptpra and three clones contained genuine mLAR cDNAs. The Ptprc but missing in the Ptprf gene. The upward arrow points to an other cDNA clones contained mLAR homologous se­ intron present in Ptprf but absent in Ptpra and Ptprc. Exon numbers quences. In Fig. 2, the sequence of the largest mLAR for LRP and Ly-5 are according to the literature. cDNA clone, mLAR#9, is depicted alongside the de­ duced amino acid sequence. both phosphatase domains (Streuli et ah, 1988) was All three mLAR cDNAs ended in an A-rich stretch used to isolate cosmid clones, two of which, 5 and 11, in the 3' untranslated region (3' UTR) also found in repeatedly showed stronger hybridization signals un­ the hLAR mRNA message (position 6900, Streuli et al., der more stringent washing conditions. These clones 1988). Screening of the mouse cDNA library w ith a were characterized further. Southern blot and restric­ more 3' UTR hLA R probe (SaZI—2£coRI, positions tion enzyme analyses revealed that these two clones 5933-7700, Streuli et ah, 1988) yielded additional overlap and span some 50 kb of the mouse Ptprf locus, clones that terminated at the genuine polyadenylation

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FIG. 4. Chromosomal localization of the Ptprf gene. Unique hybridizing signals of cosmid mLAR#5 were recorded in more than 30 metaphase spreads (right). Positively imaged chromosomes were counter stained with DAPI for the identification of the individual chromo­ somal subbands (left). 1 2 8 SCHAAPVELD ET AL. site as predicted fromhLAR sequence data (not shown). - raLARl We therefore conclude that clone mLAR# 9 represents a mLAR cDNA in which the reverse transcription reac­ tion started at the A-rich stretch within the 3' UTR. hLARL Southern blot analysis using cDNA clone mLAR#9 as a probe revealed that the sequence encoding the mPTPSl mLAR cytoplasmic region resided in a 6.5-kb S stI- hPTPSl Bam El genomic fragment. Sequence analysis showed both phosphatase domains to be encoded by 11 exons mRPTPcrl contained within a 4.5-kb EcoRl-BamHl fragment (Fig. 1). The most 3' exon contains the last 22 codons rRPTFcrl i for the protein and the entire 3' UTR of the mRNA. hRPTPffl The intron lengths in the gene segment shown in Fig. 1 vary from only 80 bp to 0.5 kb. Comparison of the r mLAR2 deduced organization of the Ptprfgene with that of the L rLAR2 * Ptpra and Ptprc RPTPase genes (encoding for LRP and ! Ly-5, respectively, Wong et ah, 1993; Saga et a l, 1988) hLAR2 i revealed conspicuous differences (Fig. 3). Whereas the * genomic organization of the first phosphatase domain mPTP52 is similar but not identical to the second domain in all hPTP52 three PTPase family members, both mLAR phospha­ tase domains together are encoded by only 11 exons, mRPTP

f. a similar genomic organization of the region encoding FIG* 5 * A proposed phylogenetic tree of phosphatase domains 1 the phosphatase domains. Our results show clear dif­ and 2 of the human, rat, and mouse PTPases LAR, PTP<5, and RPTPcr. ferences in the gene structure of RPTPases. We propose Nucleotide sequences encoding the region that starts immediately that an ancestral gene originally contained a single after the sequence DFWRM(I/V)W(E/D) and ends before the stretch tyrosine phosphatase domain encoded by at least nine HCS AG(V/I)GR were used for both domains of mLAR (Accession No. Z37988), rLAR (M60103), hLAR (Y00815), mPTP6 (D13905), hVTPS exons. This may have been duplicated later to produce (X54133), mRPTPcx (D28530), rPTPa (A49104), and hRPTJFV RPTPases with two phosphatase domains. Subse­ (S78080). This unrooted tree was constructed on the basis of a dis­ quently, several intron losses may have occurred for tance matrix created according to the Kimura 2 -parameter model both of the phosphatase domains as well as for the (Kinrura, 1980) with a transition/transversion ratio of 2 , using the program FITCH and performing global rearrangements to verify the various types of RPTPases. One intron (between exons obtained topology. Changes in sequence input order did not alter the P and Q) still present in the P tprf gene has been re­ tree topology, The scale for branch lengths (bottom) represents the moved from the Ptpra/Ptprc ancestor. In the P tprf expected underlying number of changes per site. gene, five introns that are still present in the other two RPTPase genes have been removed (Fig. 3). The reason region around the b locus on mouse chromosome 4 (Mi- why the gene structure of the P tprf gene is so much zuno etah, 1993) and distal mouse chromosome 17 (Yan more compact than other RPTPase genes remains, et a t, 1993), respectively. Together with RNA in situ however, obscure for the moment. hybridization data, which reveal different expression patterns for mLAR, MPTP6, and mRPTPcr (R. Q. J. Chromosomal Localization of the Ptprf Gene Schaapveld, J. T. G. Schepens, and W. J. A. J. Hen­ Mouse cosmid clone mLAR#5 was used as a probe driks, unpublished results), these mapping data are in agreement with Mizuno et al. (1993) and demonstrate for fluorescence in situ hybridization to determine the chromosomal localization of the Ptprf locus. Alignment that mLAR, MPTP<5, and mRPTPa are indeed separate to G-banded chromosome images showed that the P tprf entities. gene localizes within the region C6-D1 of mouse chro­ Homology to Other Receptor-like PTPases mosome 4 (Fig. 4). Based on data on evolutionary con­ servation of chromosome segments in human and The mLAR cDNA sequence presented here is nearly mouse (Lyon and Kirby, 1993), this is in agreement identical to that of rat (Pot et al., 1991) and human with the localization of the PTPRF gene within the LAR (Streuli et al., 1988); the overall homology at the p32-p33 region of human chromosome 1 (Streuli et ah, amino acid level is 99.6 and 98.2%, respectively* The 1992). This localization is distinct from those of the homology (up to 90% at the amino acid level) to other Ptprd and Ptprs loci, which have been assigned to the type II RPTPases, MPTP5 and mRPTPcr (Mizuno et MOUSE Ptprf GENE STRUCTURE 129 al., 1993; Ogata et al., 1994), which also contain two Implications for a molecular histology. Annu. Rev. Biochem. 60: catalytic domains, a single transmembrane domain, 155-190. and, extracellular ly, eight FN-III and three Ig-like do­ Feinberg, A. P., and Vogels tein, B. (1983). A technique for radiolabel­ mains, is also striking. Indeed, we also isolated clones ing DNA restriction endonuclease fragments to high specific activ­ ity. Anal. Biochem. 132: 6-13. representing MPTP and Tonks, N. K (1994). Protein tyrosine phos­ tyrosine phosphatase in the thymus. J. Im m unol 153:4478-4487. phatases: From structure to function. Trends Cell Biol. 4: 73—76. Pot, D. A., Woodford, T. A., Remboutsika, E., Haun, R. S., and Dixon, Church, G. M., and Gilbert, W. (1984). Genomic sequencing. Proc. J. E. (1991). Cloning, bacterial expression, purification, and char­ Natl Acad. ScL USA 81: 1991-1995. acterization of the cytoplasmic domain of rat LAR, a receptor-like Deininger, P. L. (1983). Random sequencing of sonicated DNA: Appli­ protein tyrosine phosphatase. J. BioL Chem. 266: 19688-19696. cation to shotgun DNA sequence analysis. Anal. Biochem, 129: Saga, Y., Tung, J.-S., Shen, F.-W., Pancoast, T. C., and Boyse, E. A. 216-223. (1988). Organization of the Ly-5 gene. Mol. Cell. BioL 8 : 4389- Devereux, J., Haeberli, P., and Smithies, 0. (1984). A comprehensive 4895. set of sequence analysis programs for the VAX. Nucleic Acids Res. Sap, J., Jiang, Y.-P., Friedlander, D., Grumet, M., and Schlessinger, 12: 387-395. J. (1994). Receptor tyrosine phosphatase R-PTP/c mediates homo- Edehnan, G. M., and Crossin, K. L. (1991). Cell adhesion molecules: philic binding. Mol. Cell. Biol. 14: 1—9. 130 SCHAAPVELD ET AL.

Streuli, M., Krueger, N. X., Hall, L, R., Schlossman, S. F., and Saito, tion of further chromosome 1 2 aberrations by competitive in situ H, (1988). A new member of the immunoglobulin superfamily that hybridization. Am. J . Hum. Genet 48: 269-273. has a cytoplasmic region homologous to the leukocyte common Tan, X., Stover, D. R., and Walsh, K. A. (1993). Demonstration of antigen. «7. Exp. Med. 168: 1563-1562. protein tyrosine phosphatase activity in the second of two homolo- > gous domains of CD45. J. Biol. Cherrt. 268: 6835—6838. Streuli, M., Krueger, N. X., Thai, T., Tang, M., and Saito, H. (1990). Tonks, N. K , Yang, Q., Flint, A. J., Gebbink, M. F. B. G., Franza, Distinct functional roles of the two intracellular phosphatase like B. R., Jr., Hill, D. E., Sun, H., and Brady-Kalnay, S. (1992). Protein domains of the receptor-linked protein tyrosine phosphatases LCA tyrosine phosphatases: The problems of a growing family, Cold and LAR EM BO J. 9; 2399-2407. Spring Harbor Symp. Quant Biol. 57: 87-94. Streuli, M., Krueger, N. X,, Ariniello, P. D., Tang, M,, Munro, J. M,, Wang, Y., and Pallen, C. J. (1991). The receptor-linked protein tyro­ Blattler, W. A., Adler, D. A., Disteche, C. M., and Saito, H. (1992). sine phosphatase HPTPcv has two catalytic domains with distinct Expression of the receptor-linked protein tyrosine phosphatase substrate specificities. EMBO J. 10: 3231-3237. LAR; Proteolytic cleavage and shedding of the CAM-like extracel­ Wong, E, C. C., Mullersman, J. E., and Thomas, M. L. (1993). Leuko­ lular structure. EMBO J, 11: 897-907. cyte common antigen-related phosphatase (LRP) gene structure: Conservation of the genomic organization of transmembrane pro­ Suijkerbuijk, E. F., van de Veen, A. Y., van Echten, J., Buys, tein tyrosine phosphatases. Genomics 17: 33-38. C. H. C. M., de Jong, B,, Oosterhuis, J. WM Warburton, D. A., Yan, H., Grossman, A., Wang, H., D’Eustachio, P., Mossie, K , Musac- Cassiman, J. J., Schonk, D., and Geurts van Kessel, A. (1991). chio, J. M,, Silvennoinen, O., and Schlessinger, J. (1993). A novel Demonstration of the genuine iso(12p) character of the standard receptor tyrosine phosphatase-cr that is highly expressed in the marker chromosome of testicular germ cell tumors and identifica­ nervous system. J . Biol. Ckem. 268: 24880-24886.