scholarly journals TANGO1 and SEC12 are co-packaged with procollagen I to facilitate the generation of large COPII carriers

2018 ◽  
Author(s):  
Lin Yuan ◽  
Samuel J Kenny ◽  
Juliet Hemmati ◽  
Ke Xu ◽  
Randy Schekman
Keyword(s):  
Endoplasmic Reticulum ◽  
Coated Vesicles ◽  
Initiation Factor ◽  
Interacting Protein ◽  
Transport Vesicles ◽  
Er Exit Sites ◽  
Copii Vesicles ◽  
Er Membrane

AbstractLarge COPII-coated vesicles serve to convey the large cargo procollagen I (PC1) from the endoplasmic reticulum (ER). The link between large cargo in the lumen of the ER and modulation of the COPII machinery remains unresolved. TANGO1 is required for procollagen (PC) secretion and interacts with PC and COPII on opposite sides of the ER membrane, but evidence suggests that TANGO1 is retained in the ER, and not included in normal size (<100nm) COPII vesicles. Here we show that TANGO1 is exported out of the ER in large COPII-coated PC1 carriers, and retrieved back to the ER by the retrograde coat, COPI, mediated by the C-terminal RDEL retrieval sequence of HSP47. TANGO1 is known to target the COPII initiation factor SEC12 to ER exit sites through an interacting protein, cTAGE5. SEC12 is important for the growth of COPII vesicles, but it is not sorted into small budded vesicles. We found both cTAGE5 and SEC12 were exported with TANGO1 in large COPII carriers. In contrast to its exclusion from small transport vesicles, SEC12 was particularly enriched around ER membranes and large COPII carriers that contained PC1. We constructed a split GFP system to recapitulate the targeting of SEC12 to PC1 via the luminal domain of TANGO1. The minimal targeting system enriched SEC12 around PC1 and generated large PC1 carriers. We conclude that TANGO1, cTAGE5, and SEC12 are co-packed with PC1 into COPII carriers to increase the size of COPII thus ensuring the capture of large cargo.

scholarly journals TANGO1 and SEC12 are copackaged with procollagen I to facilitate the generation of large COPII carriers

2018 ◽  
Vol 115 (52) ◽  
pp. E12255-E12264 ◽  
Author(s):  
Lin Yuan ◽  
Samuel J. Kenny ◽  
Juliet Hemmati ◽  
Ke Xu ◽  
Randy Schekman
Keyword(s):  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Protein Complex ◽  
Coated Vesicles ◽  
Initiation Factor ◽  
Interacting Protein ◽  
Complex Ii ◽  
Transport Vesicles ◽  
Er Exit Sites ◽  
Copii Vesicles

Large coat protein complex II (COPII)-coated vesicles serve to convey the large cargo procollagen I (PC1) from the endoplasmic reticulum (ER). The link between large cargo in the lumen of the ER and modulation of the COPII machinery remains unresolved. TANGO1 is required for PC secretion and interacts with PC and COPII on opposite sides of the ER membrane, but evidence suggests that TANGO1 is retained in the ER, and not included in normal size (<100 nm) COPII vesicles. Here we show that TANGO1 is exported out of the ER in large COPII-coated PC1 carriers, and retrieved back to the ER by the retrograde coat, COPI, mediated by the C-terminal RDEL retrieval sequence of HSP47. TANGO1 is known to target the COPII initiation factor SEC12 to ER exit sites through an interacting protein, cTAGE5. SEC12 is important for the growth of COPII vesicles, but it is not sorted into small budded vesicles. We found both cTAGE5 and SEC12 were exported with TANGO1 in large COPII carriers. In contrast to its exclusion from small transport vesicles, SEC12 was particularly enriched around ER membranes and large COPII carriers that contained PC1. We constructed a split GFP system to recapitulate the targeting of SEC12 to PC1 via the luminal domain of TANGO1. The minimal targeting system enriched SEC12 around PC1 and generated large PC1 carriers. We conclude that TANGO1, cTAGE5, and SEC12 are copacked with PC1 into COPII carriers to increase the size of COPII, thus ensuring the capture of large cargo.

scholarly journals Vesicular and uncoated Rab1-dependent cargo carriers facilitate ER to Golgi transport

2020 ◽  
Vol 133 (14) ◽  
pp. jcs239814 ◽  
Author(s):  
Laura M. Westrate ◽  
Melissa J. Hoyer ◽  
Michael J. Nash ◽  
Gia K. Voeltz
Keyword(s):  
Endoplasmic Reticulum ◽  
De Novo ◽  
Coated Vesicle ◽  
First Person ◽  
Coat Proteins ◽  
Animal Cells ◽  
Golgi Transport ◽  
Er Exit Sites ◽  
Copii Vesicles ◽  
Export System

ABSTRACTSecretory cargo is recognized, concentrated and trafficked from endoplasmic reticulum (ER) exit sites (ERES) to the Golgi. Cargo export from the ER begins when a series of highly conserved COPII coat proteins accumulate at the ER and regulate the formation of cargo-loaded COPII vesicles. In animal cells, capturing live de novo cargo trafficking past this point is challenging; it has been difficult to discriminate whether cargo is trafficked to the Golgi in a COPII-coated vesicle. Here, we describe a recently developed live-cell cargo export system that can be synchronously released from ERES to illustrate de novo trafficking in animal cells. We found that components of the COPII coat remain associated with the ERES while cargo is extruded into COPII-uncoated, non-ER associated, Rab1 (herein referring to Rab1a or Rab1b)-dependent carriers. Our data suggest that, in animal cells, COPII coat components remain stably associated with the ER at exit sites to generate a specialized compartment, but once cargo is sorted and organized, Rab1 labels these export carriers and facilitates efficient forward trafficking.This article has an associated First Person interview with the first author of the paper.

scholarly journals Erv14p Directs a Transmembrane Secretory Protein into COPII-coated Transport Vesicles

2002 ◽  
Vol 13 (3) ◽  
pp. 880-891 ◽  
Author(s):  
Jacqueline Powers ◽  
Charles Barlowe
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Integral Membrane Protein ◽  
Secretory Protein ◽  
Conserved Residues ◽  
Early Secretory Pathway ◽  
Transport Vesicles ◽  
Copii Vesicle ◽  
Copii Vesicles ◽  
Selection Of

Erv14p is a conserved integral membrane protein that traffics in COPII-coated vesicles and localizes to the early secretory pathway in yeast. Deletion of ERV14 causes a defect in polarized growth because Axl2p, a transmembrane secretory protein, accumulates in the endoplasmic reticulum and is not delivered to its site of function on the cell surface. Herein, we show that Erv14p is required for selection of Axl2p into COPII vesicles and for efficient formation of these vesicles. Erv14p binds to subunits of the COPII coat and binding depends on conserved residues in a cytoplasmically exposed loop domain of Erv14p. When mutations are introduced into this loop, an Erv14p-Axl2p complex accumulates in the endoplasmic reticulum, suggesting that Erv14p links Axl2p to the COPII coat. Based on these results and further genetic experiments, we propose Erv14p coordinates COPII vesicle formation with incorporation of specific secretory cargo.

scholarly journals The Ca2+-binding Protein ALG-2 Is Recruited to Endoplasmic Reticulum Exit Sites by Sec31A and Stabilizes the Localization of Sec31A

2006 ◽  
Vol 17 (11) ◽  
pp. 4876-4887 ◽  
Author(s):  
Akinori Yamasaki ◽  
Katsuko Tani ◽  
Akitsugu Yamamoto ◽  
Naomi Kitamura ◽  
Masayuki Komada
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Binding Protein ◽  
Small Gtpase ◽  
Dependent Manner ◽  
Rich Region ◽  
Linked Gene ◽  
Transport Vesicles ◽  
Er Exit Sites ◽  
A Cell

The formation of transport vesicles that bud from endoplasmic reticulum (ER) exit sites is dependent on the COPII coat made up of three components: the small GTPase Sar1, the Sec23/24 complex, and the Sec13/31 complex. Here, we provide evidence that apoptosis-linked gene 2 (ALG-2), a Ca2+-binding protein of unknown function, regulates the COPII function at ER exit sites in mammalian cells. ALG-2 bound to the Pro-rich region of Sec31A, a ubiquitously expressed mammalian orthologue of yeast Sec31, in a Ca2+-dependent manner and colocalized with Sec31A at ER exit sites. A Ca2+binding-deficient ALG-2 mutant, which did not bind Sec31A, lost the ability to localize to ER exit sites. Overexpression of the Pro-rich region of Sec31A or RNA interference-mediated Sec31A depletion also abolished the ALG-2 localization at these sites. In contrast, depletion of ALG-2 substantially reduced the level of Sec31A associated with the membrane at ER exit sites. Finally, treatment with a cell-permeable Ca2+chelator caused the mislocalization of ALG-2, which was accompanied by a reduced level of Sec31A at ER exit sites. We conclude that ALG-2 is recruited to ER exit sites via Ca2+-dependent interaction with Sec31A and in turn stabilizes the localization of Sec31A at these sites.

scholarly journals The odd one out: Arabidopsis reticulon20 has a role in lipid biosynthesis

2017 ◽  
Author(s):  
Verena Kriechbaumer ◽  
Lilly Maneta-Peyret ◽  
Stanley W Botchway ◽  
Jessica Upson ◽  
Louise Hughes ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Sterol Composition ◽  
Lipid Biosynthesis ◽  
Transmembrane Domains ◽  
Eukaryotic Cells ◽  
The Family ◽  
Er Exit Sites ◽  
Punctate Pattern ◽  
Er Membrane

AbstractThe family of reticulon proteins has been shown to be involved in a variety of functions in eukaryotic cells including tubulation of the endoplasmic reticulum (ER), formation of cell plates and primary plasmodesmata. Reticulons are integral ER membrane proteins characterised by a reticulon homology domain comprising four transmembrane domains which results in the reticulons sitting in the membrane in a W-topology. Here we report on a subgroup of reticulons with an extended N-terminal domain and in particular on arabidopsis reticulon 20. We show that reticulon 20 is located in a unique punctate pattern on the ER membrane. Its closest homologue reticulon 19 labels the whole ER. We show that mutants in RTN20 or RTN19, respectively, display a significant change in sterol composition in the roots indicating a role in lipid biosynthesis or regulation. A third homologue in this family - 3BETAHSD/D1- is localised to ER exit sites resulting in an intriguing location difference for the three proteins.

scholarly journals Endoplasmic Reticulum Export of Glycosyltransferases Depends on Interaction of a Cytoplasmic Dibasic Motif with Sar1

2003 ◽  
Vol 14 (9) ◽  
pp. 3753-3766 ◽  
Author(s):  
Claudio G. Giraudo ◽  
Hugo J.F. Maccioni
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Type I ◽  
Type Ii ◽  
Transport Vesicles ◽  
Microsomal Membranes ◽  
Copii Vesicles ◽  
Er Export ◽  
Selective Process ◽  
Selection Of

Membrane proteins exit the endoplasmic reticulum (ER) in COPII-transport vesicles. ER export is a selective process in which transport signals present in the cytoplasmic tail (CT) of cargo membrane proteins must be recognized by coatomer proteins for incorporation in COPII vesicles. Two classes of ER export signals have been described for type I membrane proteins, the diacidic and the dihydrophobic motifs. Both motifs participate in the Sar1-dependent binding of Sec23p–Sec24p complex to the CTs during early steps of cargo selection. However, information concerning the amino acids in the CTs that interact with Sar1 is lacking. Herein, we describe a third class of ER export motif, [RK](X)[RK], at the CT of Golgi resident glycosyltransferases that is required for these type II membrane proteins to exit the ER. The dibasic motif is located proximal to the transmembrane border, and experiments of cross-linking in microsomal membranes and of binding to immobilized peptides showed that it directly interacts with the COPII component Sar1. Sar1GTP-bound to immobilized peptides binds Sec23p. Collectively, the present data suggest that interaction of the dibasic motif with Sar1 participates in early steps of selection of Golgi resident glycosyltransferases for transport in COPII vesicles.

Regulation of ER-associated degradation via p97/VCP-interacting motif

2008 ◽  
Vol 36 (5) ◽  
pp. 818-822 ◽  
Author(s):  
Petek Ballar ◽  
Shengyun Fang
Keyword(s):  
Endoplasmic Reticulum ◽  
Ubiquitin Ligase ◽  
Terminal Region ◽  
Misfolded Proteins ◽  
Interacting Protein ◽  
Aaa Atpase ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Er Membrane

p97/VCP (valosin-containing protein) is a cytosolic AAA (ATPase associated with various cellular activities) essential for retrotranslocation of misfolded proteins during ERAD [ER (endoplasmic reticulum)-associated degradation]. gp78, an ERAD ubiquitin ligase, is one of the p97/VCP recruitment proteins localized to the ER membrane. A newly identified VIM (p97/VCP-interacting motif) in gp78 has brought about novel insights into mechanisms of ERAD, such as the presence of a p97/VCP-dependent but Ufd1-independent retrotranslocation during gp78-mediated ERAD. Additionally, SVIP (small p97/VCP-interacting protein), which contains a VIM in its N-terminal region, negatively regulates ERAD by uncoupling p97/VCP and Derlin1 from gp78. Thus SVIP may protect cells from damage by extravagant ERAD.

scholarly journals Erv26p Directs Pro-Alkaline Phosphatase into Endoplasmic Reticulum–derived Coat Protein Complex II Transport Vesicles

2006 ◽  
Vol 17 (11) ◽  
pp. 4780-4789 ◽  
Author(s):  
Catherine A. Bue ◽  
Christine M. Bentivoglio ◽  
Charles Barlowe
Keyword(s):  
Alkaline Phosphatase ◽  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Membrane Protein ◽  
Protein Complex ◽  
Integral Membrane Protein ◽  
Secretory Proteins ◽  
Complex Ii ◽  
Transport Vesicles ◽  
Copii Vesicles

Secretory proteins are exported from the endoplasmic reticulum (ER) in transport vesicles formed by the coat protein complex II (COPII). We detected Erv26p as an integral membrane protein that was efficiently packaged into COPII vesicles and cycled between the ER and Golgi compartments. The erv26Δ mutant displayed a selective secretory defect in which the pro-form of vacuolar alkaline phosphatase (pro-ALP) accumulated in the ER, whereas other secretory proteins were transported at wild-type rates. In vitro budding experiments demonstrated that Erv26p was directly required for packaging of pro-ALP into COPII vesicles. Moreover, Erv26p was detected in a specific complex with pro-ALP when immunoprecipitated from detergent-solublized ER membranes. Based on these observations, we propose that Erv26p serves as a transmembrane adaptor to link specific secretory cargo to the COPII coat. Because ALP is a type II integral membrane protein in yeast, these findings imply that an additional class of secretory cargo relies on adaptor proteins for efficient export from the ER.

scholarly journals Drosophila Sec16 Mediates the Biogenesis of tER Sites Upstream of Sar1 through an Arginine-Rich Motif

2008 ◽  
Vol 19 (10) ◽  
pp. 4352-4365 ◽  
Author(s):  
Viorica Ivan ◽  
Gert de Voer ◽  
Despina Xanthakis ◽  
Kirsten M. Spoorendonk ◽  
Vangelis Kondylis ◽  
...  
Keyword(s):  
Coated Vesicles ◽  
Rich Domain ◽  
Copii Vesicles ◽  
Arginine Rich Motif ◽  
Er Membrane

tER sites are specialized cup-shaped ER subdomains characterized by the focused budding of COPII vesicles. Sec16 has been proposed to be involved in the biogenesis of tER sites by binding to COPII coat components and clustering nascent-coated vesicles. Here, we show that Drosophila Sec16 (dSec16) acts instead as a tER scaffold upstream of the COPII machinery, including Sar1. We show that dSec16 is required for Sar1-GTP concentration to the tER sites where it recruits in turn the components of the COPII machinery to initiate coat assembly. Last, we show that the dSec16 domain required for its localization maps to an arginine-rich motif located in a nonconserved region. We propose a model in which dSec16 binds ER cups via its arginine-rich domain, interacts with Sar1-GTP that is generated on ER membrane by Sec12 and concentrates it in the ER cups where it initiates the formation of COPII vesicles, thus acting as a tER scaffold.

scholarly journals Auxilin facilitates membrane traffic in the early secretory pathway

2016 ◽  
Vol 27 (1) ◽  
pp. 127-136 ◽  
Author(s):  
Jingzhen Ding ◽  
Verónica A. Segarra ◽  
Shuliang Chen ◽  
Huaqing Cai ◽  
Sandra K. Lemmon ◽  
...  
Keyword(s):  
Secretory Pathway ◽  
Protein Complexes ◽  
Coated Vesicles ◽  
Genetic Approach ◽  
Vesicle Budding ◽  
Early Secretory Pathway ◽  
Transport Vesicles ◽  
Copii Vesicles ◽  
Mutant Cells ◽  
Analogous Function

Coat protein complexes contain an inner shell that sorts cargo and an outer shell that helps deform the membrane to give the vesicle its shape. There are three major types of coated vesicles in the cell: COPII, COPI, and clathrin. The COPII coat complex facilitates vesicle budding from the endoplasmic reticulum (ER), while the COPI coat complex performs an analogous function in the Golgi. Clathrin-coated vesicles mediate traffic from the cell surface and between the trans-Golgi and endosome. While the assembly and structure of these coat complexes has been extensively studied, the disassembly of COPII and COPI coats from membranes is less well understood. We describe a proteomic and genetic approach that connects the J-domain chaperone auxilin, which uncoats clathrin-coated vesicles, to COPII and COPI coat complexes. Consistent with a functional role for auxilin in the early secretory pathway, auxilin binds to COPII and COPI coat subunits. Furthermore, ER–Golgi and intra-Golgi traffic is delayed at 15°C in swa2Δ mutant cells, which lack auxilin. In the case of COPII vesicles, we link this delay to a defect in vesicle fusion. We propose that auxilin acts as a chaperone and/or uncoating factor for transport vesicles that act in the early secretory pathway.

Sign in / Sign up

Export Citation Format

Share Document