DOCSLIB.ORG

Retrograde Traffic from the Golgi to the Endoplasmic Reticulum

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Retrograde Traffic from the Golgi to the Endoplasmic Reticulum Downloaded from http://cshperspectives.cshlp.org/ on September 24, 2021 - Published by Cold Spring Harbor Laboratory Press Retrograde Traffic from the Golgi to the Endoplasmic Reticulum Anne Spang University of Basel, Biozentrum, Growth & Development, Klingelbergstrasse 70, 4056 Basel, Switzerland Correspondence: [email protected] Proteins to be secreted are transported from the endoplasmic reticulum (ER) to the Golgi apparatus. The transport of these proteins requires the localization and activityof proteins that create ER exit sites, coat proteins to collect cargo and to reshape the membrane into a transport container, and address labels—SNARE proteins—to target the vesicles specifically to the Golgi apparatus. In addition some proteins may need export chaperones or export receptors to enable their exit into transport vesicles. ER export factors, SNAREs, and mis- folded Golgi-resident proteins must all be retrieved from the Golgi to the ER again. This retrieval is also part of the organellar homeostasis pathway essential to maintaining the identity of the ER and of the Golgi apparatus. In this review, I will discuss the different processes in retrograde transport from the Golgi to the ER and highlight the mechanistic insights we have obtained in the last couple of years. roteins that are exposed at the plasma mem- It is assumed that the vesicle coat is at least Pbrane or populate a membrane-bounded or- partially destabilized through the hydrolysis of ganelle are synthesized into the endoplasmic GTP by the small GTPase Sar1 (Oka and Nakano reticulum (ER). In the ER, the folding of these 1994; Springeret al. 1999). However, some of the proteins takes place and posttranslational mod- destabilized coat components have to stayon the ifications such as N-glycosylation and disulfide vesicle until it has reached the Golgi apparatus bridge formation occur. Upon adopting a suit- because coat components participate in the rec- able, often correct, conformation, proteins des- ognition and the tethering process (Barlowe tined to locations beyond the ER are concen- 1997; Cai et al. 2007; Lord et al. 2011; Zong trated at so-called ER exit sites (ERES) and et al. 2012). Subsequently, SNARE proteins on incorporated into nascent COPII-coated vesi- the vesicles (v-SNAREs) zipper up with cognate cles. These COPII vesicles eventually bud off SNAREs on the Golgi (target SNAREs, t- the ER membrane and are transported to the SNAREs) to drive membrane fusion (Hay et al. Golgi (in yeast, Drosophila, and C. elegans)or 1998; Cao and Barlowe 2000; Parlati et al. 2002). the ER-Golgi intermediate compartment (in The content of the ER-derived COPII vesicles mammalian cells) (Schweizer et al. 1990; Kon- is thereby released into the lumen of the cis- dylis and Rabouille 2003; Spang 2009; Witte cisterna of the Golgi apparatus. Most proteins et al. 2011). will continue their journey through the Golgi Editors: Susan Ferro-Novick, Tom A. Rapoport, and Randy Schekman Additional Perspectives on The Endoplasmic Reticulum available at www.cshperspectives.org Copyright # 2013 Cold Spring Harbor Laboratory Press; all rights reserved; doi: 10.1101/cshperspect.a013391 Cite this article as Cold Spring Harb Perspect Biol 2013;5:a013391 1 Downloaded from http://cshperspectives.cshlp.org/ on September 24, 2021 - Published by Cold Spring Harbor Laboratory Press A. Spang apparatus and encounter further modifications coat is recruited with the ability to deform the such as extension of the glycosylation tree or membrane of the donor compartment. This lipidation. However, some proteins, especially outer coat layer also plays an important role in those involved in the fusion process, i.e., the v- determining the size of the transport vesicle. SNAREs or proteins that act as export factors of The binding of the second layer/outer shell the ER, such as Vma21, which is essential for drives polymerization of the coat, which leads export of the correctly folded and assembled to the deformation of the membrane. Finally,the V0 sector of the V-ATPase, need to be recycled transport vesicle is formed and fission from the back to the ER for another round of transport donor compartment needs to occur. In the case (Ballensiefen et al. 1998; Malkus et al. 2004). of clathrin-coated vesicles dynamin, a GTPase Moreover, cis-Golgi proteins are returned to with the ability to polymerize and form a tight the ER for quality/functional control (Todorow constriction, binds to the base of the vesicle and et al. 2000; Sato et al. 2004; Valkova et al. 2011). drives scission (van der Bliek et al. 1993; Hin- Finally, some ER-resident proteins, such as the shaw and Schmid 1995; Takei et al. 1995). In all ER Hsp70 chaperone BiP/Kar2, can escape the other vesicle budding scenarios, the mechanistic ER, but are captured at the cis-Golgi by the H/ basis for severing the vesicle from the donor KDEL receptor Erd2 and returned to the ER membrane is much less clear, although a direct (Lewis et al. 1990; Semenza et al. 1990; Aoe role of the Arf1/Sar1 GTPases has been pro- et al. 1997). posed because each of them can oligomerize Unfortunately, the retrograde transport and cause tubulation of liposomes invitro (Bielli route is also hijacked by toxins. For example, et al. 2005; Lee et al. 2005a; Beck et al. 2008, endocytosed cholera toxin subunit A contains 2011). a KDEL sequence and can thereby exploit the The players at the cis-Golgi involved in COPI system to access the ER (Majoul et al. 1996, vesicle formation follow the general scheme out- 1998). From there, it is retro-translocated into lined above, beginning with the GEF at the cis- the cytoplasm where it can exert its detrimental Golgi, GBF1 (Gea1/2 in yeast) (Peyroche et al. function. 1996, 2001; Spang et al. 2001; Zhao et al. 2006). How the GEF is itself recruited is not entirely clear. One determinant appears to be the phos- VESICLE FORMATION AT THE GOLGI phoinositide PI4P (Dumaresq-Doiron et al. APPARATUS 2010). However, lipid binding cannot account for the specific recruitment of the GEF to the cis COPI Vesicles face of the Golgi. How the temporal and spatial Most transport vesicle formation appears to fol- control of GBF1 Golgi localization is achieved low an evolutionarily and structurally conserved would be an important piece of information, as scheme. First, a small GTPase of the Arf1/Sar1 the localization of the GEF determines where family is recruited to the membrane by the ac- the small GTPase Arf1 is activated. Upon acti- tion of a guanine nucleotide exchange factor vation, Arf1 is recruited to the Golgi, where it (GEF). Then a layer of the coat binds to the initiates the binding of the heptameric coat activated small GTPase and recruits cargo at complex, coatomer. This complex can be divid- the same time. If there is enough cargo avail- ed up into two layers: a tetrameric subcomplex able, the GTPase.coat.cargo complex is stabi- resembling adaptor complexes of the clathrin lized. Interestingly, this first inner layer of the coat and a cage-like trimeric subcomplex possi- coat also contains a GTPase activating protein bly containing the membrane-deforming abili- (GAP), which thus becomes an intrinsic part of ty of the complex (Yu et al. 2012). Two Arf1 the coat complex. However, the arrangement in proteins interact with the tetrameric subcom- this prebudding complex is such that the GAP plex to initiate membrane recruitment of coat- cannot efficiently stimulate the GTPase activity omer (Yu et al. 2012). In the case of COPI ves- of the small GTPase. Next, a second layer of the icles, the first and second layers of the coat are 2 Cite this article as Cold Spring Harb Perspect Biol 2013;5:a013391 Downloaded from http://cshperspectives.cshlp.org/ on September 24, 2021 - Published by Cold Spring Harbor Laboratory Press Retrograde Traffic from the Golgi to the ER thought to be recruited simultaneously. This is liberate the nascent vesicle from the donor because the coatomer complex exists as a pre- membrane, and hence act early in vesicle bio- assembled heptameric complex in the cyto- genesis. In contrast, Glo3 (ArfGAP2/3) would plasm (Waters et al. 1991; Hosobuchi et al. stabilize the coat on the nascent vesicle and fi- 1992; Robinson and Kreis 1992; Hara-Kuge nally would initiate uncoating by stimulating et al. 1994). Furthermore, the purified hepta- GTP hydrolysis on Arf1; this latter function be- meric complex, together with activated Arf1 ing probably required late in the vesicle’s life- and guanine nucleotides, is sufficient to gener- time. ate COPI-coated vesicles from synthetic lipo- Before it can fuse with a target compart- somes (Spang et al. 1998). However, different ment, a vesicle’s coat must be at least partially types of the coatomer complexes exist, one of disassembled or destabilized. This led us to ask which appears to act at the level of endosomes when uncoating would occur. Multiple scenar- (Whitney et al. 1995; Aniento et al. 1996; Gu ios have been discussed for COPI and COPII et al. 1997). Here, we will concentrate on the vesicles. It is assumed, as discussed above, that coatomer complex at the cis-Golgi. generation and consumption of COPI and The coatomer complex by itself is unable COPII vesicles follow a very similar mechanism. to stimulate GTP hydrolysis by Arf1; ArfGAPs Therefore, I will use the following findings from have to be included and are intrinsic parts of the either COPI or COPII vesicles to illustrate our coat. Although in yeast two different ArfGAPs, current understanding of uncoating. Initially, it Gcs1 and Glo3, have partially overlapping func- was believed that uncoating occurs just before tions in COPI vesicle formation and can substi- the fusion event; the coat might therefore play tute for each other (Poon et al.
Load more

Recommended publications
  • Mea6 Controls VLDL Transport Through the Coordinated Regulation of COPII Assembly
    Cell Research (2016) 26:787-804. npg © 2016 IBCB, SIBS, CAS All rights reserved 1001-0602/16 $ 32.00 ORIGINAL ARTICLE www.nature.com/cr Mea6 controls VLDL transport through the coordinated regulation of COPII assembly Yaqing Wang1, *, Liang Liu1, 2, *, Hongsheng Zhang1, 2, Junwan Fan1, 2, Feng Zhang1, 2, Mei Yu3, Lei Shi1, Lin Yang1, Sin Man Lam1, Huimin Wang4, Xiaowei Chen4, Yingchun Wang1, Fei Gao5, Guanghou Shui1, Zhiheng Xu1, 6 1State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; 2University of Chinese Academy of Sciences, Beijing 100101, China; 3School of Life Science, Shandong University, Jinan 250100, China; 4Institute of Molecular Medicine, Peking University, Beijing 100871, China; 5State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; 6Translation- al Medical Center for Stem Cell Therapy, Shanghai East Hospital, Tongji University School of Medicine, Shanghai 200120, China Lipid accumulation, which may be caused by the disturbance in very low density lipoprotein (VLDL) secretion in the liver, can lead to fatty liver disease. VLDL is synthesized in endoplasmic reticulum (ER) and transported to Golgi apparatus for secretion into plasma. However, the underlying molecular mechanism for VLDL transport is still poor- ly understood. Here we show that hepatocyte-specific deletion of meningioma-expressed antigen 6 (Mea6)/cutaneous T cell lymphoma-associated antigen 5C (cTAGE5C) leads to severe fatty liver and hypolipemia in mice. Quantitative lip- idomic and proteomic analyses indicate that Mea6/cTAGE5 deletion impairs the secretion of different types of lipids and proteins, including VLDL, from the liver.
    [Show full text]
  • Formation of COPI-Coated Vesicles at a Glance Eric C
    © 2018. Published by The Company of Biologists Ltd | Journal of Cell Science (2018) 131, jcs209890. doi:10.1242/jcs.209890 CELL SCIENCE AT A GLANCE Formation of COPI-coated vesicles at a glance Eric C. Arakel1 and Blanche Schwappach1,2,* ABSTRACT unresolved, this review attempts to refocus the perspectives of The coat protein complex I (COPI) allows the precise sorting of lipids the field. and proteins between Golgi cisternae and retrieval from the Golgi KEY WORDS: Arf1, ArfGAP, COPI, Coatomer, Golgi, Endoplasmic to the ER. This essential role maintains the identity of the early reticulum, Vesicle coat secretory pathway and impinges on key cellular processes, such as protein quality control. In this Cell Science at a Glance and accompanying poster, we illustrate the different stages of COPI- Introduction coated vesicle formation and revisit decades of research in the Vesicle coat proteins, such as the archetypal clathrin and the coat context of recent advances in the elucidation of COPI coat structure. protein complexes II and I (COPII and COPI, respectively) are By calling attention to an array of questions that have remained molecular machines with two central roles: enabling vesicle formation, and selecting protein and lipid cargo to be packaged within them. Thus, coat proteins fulfil a central role in the 1Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee homeostasis of the cell’s endomembrane system and are the basis 23, 37073 Göttingen, Germany. 2Max-Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany. of functionally segregated compartments. COPI operates in retrieval from the Golgi to the endoplasmic reticulum (ER) and in intra-Golgi *Author for correspondence ([email protected]) transport (Beck et al., 2009; Duden, 2003; Lee et al., 2004a; Spang, E.C.A., 0000-0001-7716-7149; B.S., 0000-0003-0225-6432 2009), and maintains ER- and Golgi-resident chaperones and enzymes where they belong.
    [Show full text]
  • Mechanisms of Synaptic Plasticity Mediated by Clathrin Adaptor-Protein Complexes 1 and 2 in Mice
    Mechanisms of synaptic plasticity mediated by Clathrin Adaptor-protein complexes 1 and 2 in mice Dissertation for the award of the degree “Doctor rerum naturalium” at the Georg-August-University Göttingen within the doctoral program “Molecular Biology of Cells” of the Georg-August University School of Science (GAUSS) Submitted by Ratnakar Mishra Born in Birpur, Bihar, India Göttingen, Germany 2019 1 Members of the Thesis Committee Prof. Dr. Peter Schu Institute for Cellular Biochemistry, (Supervisor and first referee) University Medical Center Göttingen, Germany Dr. Hans Dieter Schmitt Neurobiology, Max Planck Institute (Second referee) for Biophysical Chemistry, Göttingen, Germany Prof. Dr. med. Thomas A. Bayer Division of Molecular Psychiatry, University Medical Center, Göttingen, Germany Additional Members of the Examination Board Prof. Dr. Silvio O. Rizzoli Department of Neuro-and Sensory Physiology, University Medical Center Göttingen, Germany Dr. Roland Dosch Institute of Developmental Biochemistry, University Medical Center Göttingen, Germany Prof. Dr. med. Martin Oppermann Institute of Cellular and Molecular Immunology, University Medical Center, Göttingen, Germany Date of oral examination: 14th may 2019 2 Table of Contents List of abbreviations ................................................................................. 5 Abstract ................................................................................................... 7 Chapter 1: Introduction ............................................................................
    [Show full text]
  • The Structure of the COPI Coat Determined Within the Cell
    RESEARCH ADVANCE The structure of the COPI coat determined within the cell Yury S Bykov1,2, Miroslava Schaffer3, Svetlana O Dodonova1†, Sahradha Albert3, Ju¨ rgen M Plitzko3, Wolfgang Baumeister3*, Benjamin D Engel3*, John AG Briggs1,2* 1Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany; 2Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom; 3Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany Abstract COPI-coated vesicles mediate trafficking within the Golgi apparatus and from the Golgi to the endoplasmic reticulum. The structures of membrane protein coats, including COPI, have been extensively studied with in vitro reconstitution systems using purified components. Previously we have determined a complete structural model of the in vitro reconstituted COPI coat (Dodonova et al., 2017). Here, we applied cryo-focused ion beam milling, cryo-electron tomography and subtomogram averaging to determine the native structure of the COPI coat within vitrified Chlamydomonas reinhardtii cells. The native algal structure resembles the in vitro mammalian structure, but additionally reveals cargo bound beneath b’–COP. We find that all coat components *For correspondence: disassemble simultaneously and relatively rapidly after budding. Structural analysis in situ, [email protected] (WB); maintaining Golgi topology, shows that vesicles change their size, membrane thickness, and cargo [email protected] (BDE); content as they progress from cis to trans, but the structure of the coat machinery remains [email protected] constant. (JAGB) DOI: https://doi.org/10.7554/eLife.32493.001 Present address: †Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Go¨ ttingen, Germany Introduction Vesicular transport between cellular compartments is a fundamental mechanism of eukaryotic cells.
    [Show full text]
  • ER-To-Golgi Trafficking and Its Implication in Neurological Diseases
    cells Review ER-to-Golgi Trafficking and Its Implication in Neurological Diseases 1,2, 1,2 1,2, Bo Wang y, Katherine R. Stanford and Mondira Kundu * 1 Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; [email protected] (B.W.); [email protected] (K.R.S.) 2 Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA * Correspondence: [email protected]; Tel.: +1-901-595-6048 Present address: School of Life Sciences, Xiamen University, Xiamen 361102, China. y Received: 21 November 2019; Accepted: 7 February 2020; Published: 11 February 2020 Abstract: Membrane and secretory proteins are essential for almost every aspect of cellular function. These proteins are incorporated into ER-derived carriers and transported to the Golgi before being sorted for delivery to their final destination. Although ER-to-Golgi trafficking is highly conserved among eukaryotes, several layers of complexity have been added to meet the increased demands of complex cell types in metazoans. The specialized morphology of neurons and the necessity for precise spatiotemporal control over membrane and secretory protein localization and function make them particularly vulnerable to defects in trafficking. This review summarizes the general mechanisms involved in ER-to-Golgi trafficking and highlights mutations in genes affecting this process, which are associated with neurological diseases in humans. Keywords: COPII trafficking; endoplasmic reticulum; Golgi apparatus; neurological disease 1. Overview Approximately one-third of all proteins encoded by the mammalian genome are exported from the endoplasmic reticulum (ER) and transported to the Golgi apparatus, where they are sorted for delivery to their final destination in membrane compartments or secretory vesicles [1].
    [Show full text]
  • The Amino-Terminal Domain of the Golgi Protein Giantin Interacts Directly with the Vesicle-Tethering Protein P115*
    THE JOURNAL OF BIOLOGICAL CHEMISTRY Vol. 275, No. 4, Issue of January 28, pp. 2831–2836, 2000 © 2000 by The American Society for Biochemistry and Molecular Biology, Inc. Printed in U.S.A. The Amino-terminal Domain of the Golgi Protein Giantin Interacts Directly with the Vesicle-tethering Protein p115* (Received for publication, November 10, 1999) Giovanni M. Lesa‡§¶, Joachim Seemann‡ʈ**, James Shorter‡ ‡‡, Joe¨l Vandekerckhove§§¶¶, and Graham Warren‡**ʈʈ From the ‡Cell Biology Laboratory and §Molecular Neuropathobiology Laboratory, Imperial Cancer Research Fund, 44 Lincoln’s Inn Fields, London, WC2A 3PX, United Kingdom and the §§Departments of Biochemistry and Medical Protein Research (VIB), Universiteit Gent, Ledeganckstraat 35, B-9000 Gent, Belgium Giantin is thought to form a complex with p115 and munc-18/sec1 group of proteins (22, 23). In vitro studies em- Golgi matrix protein 130, which is involved in the reas- ploying yeast vacuoles suggest that after SNARE pairing a sembly of Golgi cisternae and stacks at the end of mito- phosphatase-dependent (24) and a Ca2ϩ/calmodulin-dependent sis. The complex is involved in the tethering of coat step (25) are required for fusion. protomer I vesicles to Golgi membranes and the initial It has become increasingly clear that before SNARE pairing stacking of reforming cisternae. Here we show that the COP vesicles become tethered to target membranes. Tethering NH2-terminal 15% of Giantin suffices to bind p115 in is thought to be mediated by rod-like proteins with extensive vitro and in vivo and to block cell-free Golgi reassembly. coiled-coil (23, 26–28).
    [Show full text]
  • Cryo-Tomography of Coat Complexes ISSN 2059-7983
    research papers Visualizing membrane trafficking through the electron microscope: cryo-tomography of coat complexes ISSN 2059-7983 Evgenia A. Markova and Giulia Zanetti* Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, England. Received 8 March 2019 *Correspondence e-mail: [email protected] Accepted 12 April 2019 Coat proteins mediate vesicular transport between intracellular compartments, Keywords: cryo-electron tomography; which is essential for the distribution of molecules within the eukaryotic cell. three-dimensional reconstruction; coat proteins; The global arrangement of coat proteins on the membrane is key to their vesicular transport; COPII; subtomogram function, and cryo-electron tomography and subtomogram averaging have been averaging. used to study membrane-bound coat proteins, providing crucial structural insight. This review outlines a workflow for the structural elucidation of coat proteins, incorporating recent developments in the collection and processing of cryo-electron tomography data. Recent work on coat protein I, coat protein II and retromer performed on in vitro reconstitutions or in situ is summarized. These studies have answered long-standing questions regarding the mechanisms of membrane binding, polymerization and assembly regulation of coat proteins. 1. Introduction Recent advances in cryo-electron microscopy (cryo-EM) have enabled numerous high-resolution studies which have addressed long-standing structural biology questions. The large body of cryo-EM work carried out for protein structure characterization has utilized single-particle electron micro- scopy (Cheng, 2018). Recently, developments in hardware, data collection and data processing have placed cryo-electron tomography (cryo-ET) and subtomogram averaging (STA) at the forefront of structural studies of repetitive assemblies, reaching resolutions comparable to those of single-particle EM (Schur et al., 2016; Wan et al., 2017; Hutchings et al., 2018; Dodonova et al., 2017; Himes & Zhang, 2018).
    [Show full text]
  • Craniofacial Diseases Caused by Defects in Intracellular Trafficking
    G C A T T A C G G C A T genes Review Craniofacial Diseases Caused by Defects in Intracellular Trafficking Chung-Ling Lu and Jinoh Kim * Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-515-294-3401 Abstract: Cells use membrane-bound carriers to transport cargo molecules like membrane proteins and soluble proteins, to their destinations. Many signaling receptors and ligands are synthesized in the endoplasmic reticulum and are transported to their destinations through intracellular trafficking pathways. Some of the signaling molecules play a critical role in craniofacial morphogenesis. Not surprisingly, variants in the genes encoding intracellular trafficking machinery can cause craniofacial diseases. Despite the fundamental importance of the trafficking pathways in craniofacial morphogen- esis, relatively less emphasis is placed on this topic, thus far. Here, we describe craniofacial diseases caused by lesions in the intracellular trafficking machinery and possible treatment strategies for such diseases. Keywords: craniofacial diseases; intracellular trafficking; secretory pathway; endosome/lysosome targeting; endocytosis 1. Introduction Citation: Lu, C.-L.; Kim, J. Craniofacial malformations are common birth defects that often manifest as part of Craniofacial Diseases Caused by a syndrome. These developmental defects are involved in three-fourths of all congenital Defects in Intracellular Trafficking. defects in humans, affecting the development of the head, face, and neck [1]. Overt cranio- Genes 2021, 12, 726. https://doi.org/ facial malformations include cleft lip with or without cleft palate (CL/P), cleft palate alone 10.3390/genes12050726 (CP), craniosynostosis, microtia, and hemifacial macrosomia, although craniofacial dys- morphism is also common [2].
    [Show full text]
  • June N&V Final
    NEWS AND VIEWS studies is not fully functional, although this is disturbed, whereas binding of the calcium- our knowledge of the various steps in the not proven. An alternative explanation is that activated sytI domain would be sufficient to fusion process and their regulatory mecha- at synapses and in cells, full-length sytI (an promote SNARE zippering and fusion (Fig. 2). nisms. This might ultimately result in the integral membrane protein) is needed not only In conclusion, the results from Tucker et identification of other factors that regulate the for exocytic fusion, but also to initiate vesicle al.1 are an important milestone in the recon- system, in particular those allowing mem- docking to the plasma membrane through stitution of presynaptic events that result in brane fusion to operate in the sub-millisecond binding to SNAP25. In this case, inhibition by neurotransmitter release. On the basis of these timescale as it does in synaptic physiology. the cytosolic domain could be explained by an results, the need for proteins and lipids other 1. Tucker, W. C., Weber, T. & Chapman, E. R. Science unproductive interaction with the t-SNARE than sytI in the calcium regulation of synaptic 304, 435–438 (2004). 5,6 that prevents binding of full-length sytI (refs 9, vesicle fusion can finally be excluded. 2. Weber, T. et al. Cell 92, 759–72 (1998). 10). The reconstituted bilayers, however, could Exocytic fusion, however, is a complex process 3. Geppert, M. et al. Cell 79, 717–727 (1994). 4. Ubach, J. et al. EMBO J. 17, 3921–3930 (1998).
    [Show full text]
  • Vesicle Coats: Structure, Function, And
    Review Vesicle coats: structure, function, and general principles of assembly 1 2 2 1,3 Marco Faini , Rainer Beck , Felix T. Wieland , and John A.G. Briggs 1 Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany 2 Heidelberg University Biochemistry Center, Heidelberg University, Im Neuenheimer Feld 328, 69120 Heidelberg, Germany 3 Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany The transport of proteins and lipids between distinct The three best-characterized types of vesicular carrier cellular compartments is conducted by coated vesicles. involved in intracellular trafficking are distinguished by These vesicles are formed by the self-assembly of coat their different coat proteins and their different trafficking proteins on a membrane, leading to collection of the routes. Clathrin-coated vesicles (CCVs) act in the late vesicle cargo and membrane bending to form a bud. secretory pathway and in the endocytic pathway, Scission at the bud neck releases the vesicle. X-ray COPII-coated vesicles export proteins from the endoplas- crystallography and electron microscopy (EM) have re- mic reticulum (ER), and COPI-coated vesicles shuttle cently generated models of isolated coat components within the Golgi organelle and from the Golgi back to and assembled coats. Here, we review these data to the ER. Despite having different compartment specifici- present a structural overview of the three main coats: ties and different structural components, the mechanisms clathrin, COPII, and COPI. The three coats have similar of their formation follow similar rules. The time and place function, common ancestry, and structural similarities, at which vesicle formation occurs are most often regulated but exhibit fundamental differences in structure and by small GTP-binding proteins.
    [Show full text]
  • Selective Packaging of Cargo Molecules Into Endoplasmic Reticulum-Derived COPII Vesicles (Sar1p͞sec16p͞secretory Proteins͞snare Proteins)
    Proc. Natl. Acad. Sci. USA Vol. 94, pp. 837–842, February 1997 Biochemistry Selective packaging of cargo molecules into endoplasmic reticulum-derived COPII vesicles (Sar1pySec16pysecretory proteinsySNARE proteins) JOSEPH L. CAMPBELL AND RANDY SCHEKMAN Department of Molecular and Cell Biology, and Howard Hughes Medical Institute, Barker Hall, University of California, Berkeley, CA 94720-3202 Contributed by Randy Schekman, November 27, 1996 ABSTRACT Coated vesicles transport proteins from the Despite our knowledge of the cytosolic factors involved in endoplasmic reticulum (ER) to the Golgi apparatus. The vesicle formation, little is known about how cargo is recognized formation of transport vesicles in vitro requires the incubation and packaged into these vesicles. One class of proteins that of an ER-membrane fraction with three protein fractions must be packaged into vesicles is known collectively as collectively known as coat protein II (COPII; Sar1p, Sec23py v-SNARE [vesicle-soluble NSF (N-ethylmaleimide-sensitive Sec24p, and Sec13pySec31p). We used this assay to investigate factor) attachment protein receptor] proteins (for review, see how targeting [v-SNARE, vesicle-soluble NSF (N-ethylmale- ref. 5). v-SNARE proteins are membrane-bound proteins that imide-sensitive factor) attachment protein receptor], putative interact with their cognate t-SNARE (target SNARE) protein adapter (e.g., Emp24p), and cargo molecules are captured into (t-SNARE proteins are located in the membrane of the acceptor ER-derived COPII vesicles. Analysis of fusion proteins strongly organelle) to ensure that vesicles only fuse with the membrane of suggests that the cytoplasmic domain of the v-SNARE protein the appropriate organelle. To examine v-SNARE packaging Sec22p is required for its packaging into ER-derived COPII signals, we employed fusion proteins between Sec22p, a vesicles.
    [Show full text]
  • 1 Novel Functions of the Flippase Drs2 and the Coat Protein COPI In
    Novel Functions of the Flippase Drs2 and the Coat Protein COPI in Protein Trafficking By Hannah Marcille Hankins Dissertation Submitted to the Faculty of the Graduate School of Vanderbilt University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Biological Sciences May, 2016 Nashville, Tennessee Approved: Todd R. Graham, Ph.D Katherine L. Friedman, Ph.D. Kendal S. Broadie, Ph.D. Anne K. Kenworthy, Ph.D. Charles R. Sanders, Ph.D. 1 ACKNOWLEDGEMENTS It takes a village to raise a graduate student, and I have many villagers to thank for getting me to this point. I would never have considered doing research if it were not for my professors at Henderson State University, particularly Martin Campbell and Troy Bray, who were very supportive and encouraging throughout my undergraduate studies. I was also fortunate to be able to do full time research during the summers of my sophomore and junior years in the lab of Kevin Raney at the University of Arkansas for Medical Sciences. If it were not for the support system and these wonderful research experiences I had as an undergraduate, I never would have pursued graduate school at Vanderbilt and would not be the scientist I am today. I would like to thank my graduate school mentor, Todd Graham, for giving me the opportunity to join his lab and for introducing me to the wonderful world of yeast. Todd is an amazing and enthusiastic scientist; his guidance and support throughout my graduate career has been invaluable and I am truly grateful to have such a wonderful mentor.
    [Show full text]