Browse
Submit Data
Databases
API
Help

Dataset Information

23 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

COPII collar defines the boundary between ER and ER exit site and does not coat cargo containers.

ABSTRACT: COPII and COPI mediate the formation of membrane vesicles translocating in opposite directions within the secretory pathway. Live-cell and electron microscopy revealed a novel mode of function for COPII during cargo export from the ER. COPII is recruited to membranes defining the boundary between the ER and ER exit sites, facilitating selective cargo concentration. Using direct observation of living cells, we monitored cargo selection processes, accumulation, and fission of COPII-free ERES membranes. CRISPR/Cas12a tagging, the RUSH system, and pharmaceutical and genetic perturbations of ER-Golgi transport demonstrated that the COPII coat remains bound to the ER-ERES boundary during protein export. Manipulation of the cargo-binding domain in COPII Sec24B prohibits cargo accumulation in ERES. These findings suggest a role for COPII in selecting and concentrating exported cargo rather than coating Golgi-bound carriers. These findings transform our understanding of coat proteins' role in ER-to-Golgi transport.

SUBMITTER: Shomron O

PROVIDER: S-EPMC8054201 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

ER cargo properties specify a requirement for COPII coat rigidity mediated by Sec13p.

Project description:Eukaryotic secretory proteins exit the endoplasmic reticulum (ER) via transport vesicles generated by the essential coat protein complex II (COPII) proteins. The outer coat complex, Sec13-Sec31, forms a scaffold that is thought to enforce curvature. By exploiting yeast bypass-of-sec-thirteen (bst) mutants, where Sec13p is dispensable, we probed the relationship between a compromised COPII coat and the cellular context in which it could still function. Genetic and biochemical analyses suggested that Sec13p was required to generate vesicles from membranes that contained asymmetrically distributed cargoes that were likely to confer opposing curvature. Thus, Sec13p may rigidify the COPII cage and increase its membrane-bending capacity; this function could be bypassed when a bst mutation renders the membrane more deformable.

| S-EPMC3306526 | biostudies-literature

Structural basis for cargo regulation of COPII coat assembly.

Project description:Using cryo-electron microscopy, we have solved the structure of an icosidodecahedral COPII coat involved in cargo export from the endoplasmic reticulum (ER) coassembled from purified cargo adaptor Sec23-24 and Sec13-31 lattice-forming complexes. The coat structure shows a tetrameric assembly of the Sec23-24 adaptor layer that is well positioned beneath the vertices and edges of the Sec13-31 lattice. Fitting the known crystal structures of the COPII proteins into the density map reveals a flexible hinge region stemming from interactions between WD40 beta-propeller domains present in Sec13 and Sec31 at the vertices. The structure shows that the hinge region can direct geometric cage expansion to accommodate a wide range of bulky cargo, including procollagen and chylomicrons, that is sensitive to adaptor function in inherited disease. The COPII coat structure leads us to propose a mechanism by which cargo drives cage assembly and membrane curvature for budding from the ER.

| S-EPMC2649882 | biostudies-literature

COPII proteins exhibit distinct subdomains within each ER exit site for executing their functions.

Project description:Secretory proteins are exported from special domains of the endoplasmic reticulum (ER) termed ER exit sites, via COPII-coated carriers. We recently showed that TANGO1 and Sec16 cooperatively organize mammalian ER exit sites for efficient secretion. However, the detailed spatial organization of mammalian ER exit sites is yet to be revealed. Here, we used super-resolution confocal live imaging microscopy (SCLIM) to investigate the localization of endogenous proteins, and we identified domains abundant in transmembrane complexes (TANGO1/cTAGE5/Sec12) juxtaposed to Sec16. Interestingly, this domain can be distinguished from the inner and the outer coats of COPII proteins within each mammalian ER exit site. Cargoes are partially concentrated in the domain for secretion. Our results suggest that mammalian ER exit sites compartmentalize proteins according to their function in COPII vesicle formation.

| S-EPMC6517409 | biostudies-literature

Dimeric sorting code for concentrative cargo selection by the COPII coat.

Project description:The flow of cargo vesicles along the secretory pathway requires concerted action among various regulators. The COPII complex, assembled by the activated SAR1 GTPases on the surface of the endoplasmic reticulum, orchestrates protein interactions to package cargos and generate transport vesicles en route to the Golgi. The dynamic nature of COPII, however, hinders analysis with conventional biochemical assays. Here we apply proximity-dependent biotinylation labeling to capture the dynamics of COPII transport in cells. When SAR1B was fused with a promiscuous biotin ligase, BirA*, the fusion protein SAR1B-BirA* biotinylates and thus enables the capture of COPII machinery and cargos in a GTP-dependent manner. Biochemical and pulse-chase imaging experiments demonstrate that the COPII coat undergoes a dynamic cycle of engagement-disengagement with the transmembrane cargo receptor LMAN1/ERGIC53. LMAN1 undergoes a process of concentrative sorting by the COPII coat, via a dimeric sorting code generated by oligomerization of the cargo receptor. Similar oligomerization events have been observed with other COPII sorting signals, suggesting that dimeric/multimeric sorting codes may serve as a general mechanism to generate selectivity of cargo sorting.

| S-EPMC5889621 | biostudies-literature

SFT-4/Surf4 control ER export of soluble cargo proteins and participate in ER exit site organization.

Project description:Lipoproteins regulate the overall lipid homeostasis in animals. However, the molecular mechanisms underlying lipoprotein trafficking remain poorly understood. Here, we show that SFT-4, a Caenorhabditis elegans homologue of the yeast Erv29p, is essential for the endoplasmic reticulum (ER) export of the yolk protein VIT-2, which is synthesized as a lipoprotein complex. SFT-4 loss strongly inhibits the ER exit of yolk proteins and certain soluble cargo proteins in intestinal cells. SFT-4 predominantly localizes at ER exit sites (ERES) and physically interacts with VIT-2 in vivo, which suggests that SFT-4 promotes the ER export of soluble proteins as a cargo receptor. Notably, Surf4, a mammalian SFT-4 homologue, physically interacts with apolipoprotein B, a very-low-density lipoprotein core protein, and its loss causes ER accumulation of apolipoprotein B in human hepatic HepG2 cells. Interestingly, loss of SFT-4 and Surf4 reduced the number of COPII-positive ERES. Thus, SFT-4 and Surf4 regulate the export of soluble proteins, including lipoproteins, from the ER and participate in ERES organization in animals.

| S-EPMC5987718 | biostudies-literature

Structural basis of cargo membrane protein discrimination by the human COPII coat machinery.

Project description:Genomic analysis shows that the increased complexity of trafficking pathways in mammalian cells involves an expansion of the number of SNARE, Rab and COP proteins. Thus, the human genome encodes four forms of Sec24, the cargo selection subunit of the COPII vesicular coat, and this is proposed to increase the range of cargo accommodated by human COPII-coated vesicles. In this study, we combined X-ray crystallographic and biochemical analysis with functional assays of cargo packaging into COPII vesicles to establish molecular mechanisms for cargo discrimination by human Sec24 subunits. A conserved IxM packaging signal binds in a surface groove of Sec24c and Sec24d, but the groove is occluded in the Sec24a and Sec24b subunits. Conversely, LxxLE class transport signals and the DxE signal of VSV glycoprotein are selectively bound by Sec24a and Sec24b subunits. A comparative analysis of crystal structures of the four human Sec24 isoforms establishes the structural determinants for discrimination among these transport signals, and provides a framework to understand how an expansion of coat subunits extends the range of cargo proteins packaged into COPII-coated vesicles.

| S-EPMC2580787 | biostudies-literature

Carbohydrate- and conformation-dependent cargo capture for ER-exit.

Project description:Some secretory proteins leave the endoplasmic reticulum (ER) by a receptor-mediated cargo capture mechanism, but the signals required for the cargo-receptor interaction are largely unknown. Here, we describe a novel targeting motif that is composed of a high-mannose type oligosaccharide intimately associated with a surface-exposed peptide beta-hairpin loop. The motif accounts for lectin ERGIC-53-assisted ER-export of the lyososomal enzyme procathepsin Z. The second oligosaccharide chain of procathepsin Z exhibits no binding activity for ERGIC-53, illustrating the selective lectin properties of ERGIC-53. Our data suggest that the conformation-based motif is only present in fully folded procathepsin Z and that its recognition by ERGIC-53 reflects a quality control mechanism that acts complementary to the primary folding machinery in the ER. A similar oligosaccharide/beta-hairpin loop structure is present in cathepsin C, another cargo of ERGIC-53, suggesting the general nature of this ER-exit signal. To our knowledge this is the first documentation of an ER-exit signal in soluble cargo in conjunction with its decoding by a transport receptor.

| S-EPMC551490 | biostudies-literature

Coupling of ER exit to microtubules through direct interaction of COPII with dynactin.

Project description:Transport of proteins from the endoplasmic reticulum (ER) to the Golgi is mediated by the sequential action of two coat complexes: COPII concentrates cargo for secretion at ER export sites, then COPI is subsequently recruited to nascent carriers and retrieves recycling proteins back to the ER. These carriers then move towards the Golgi along microtubules, driven by the dynein/dynactin complexes. Here we show that the Sec23p component of the COPII complex directly interacts with the dynactin complex through the carboxy-terminal cargo-binding domain of p150(Glued). Functional assays, including measurements of the rate of recycling of COPII on the ER membrane and quantitative analyses of secretion, indicate that this interaction underlies functional coupling of ER export to microtubules. Together, our data suggest a mechanism by which membranes of the early secretory pathway can be linked to motors and microtubules for subsequent organization and movement to the Golgi apparatus.

| S-EPMC1592520 | biostudies-literature

The Sar1 GTPase is dispensable for COPII-dependent cargo export from the ER.

Project description:Coat protein complex II (COPII) plays an integral role in the packaging of secretory cargoes within membrane-enclosed transport carriers that leave the endoplasmic reticulum (ER) from discrete subdomains. Lipid bilayer remodeling necessary for this process is driven initially by membrane penetration mediated by the Sar1 GTPase and further stabilized by assembly of a multilayered complex of several COPII proteins. However, the relative contributions of these distinct factors to transport carrier formation and protein trafficking remain unclear. Here, we demonstrate that anterograde cargo transport from the ER continues in the absence of Sar1, although the efficiency of this process is dramatically reduced. Specifically, secretory cargoes are retained nearly five times longer at ER subdomains when Sar1 is depleted, but they ultimately remain capable of being translocated to the perinuclear region of cells. Taken together, our findings highlight alternative mechanisms by which COPII promotes transport carrier biogenesis.

| S-EPMC10592460 | biostudies-literature

Sit4p/PP6 regulates ER-to-Golgi traffic by controlling the dephosphorylation of COPII coat subunits.

Project description:Traffic from the endoplasmic reticulum (ER) to the Golgi complex is initiated when the activated form of the GTPase Sar1p recruits the Sec23p-Sec24p complex to ER membranes. The Sec23p-Sec24p complex, which forms the inner shell of the COPII coat, sorts cargo into ER-derived vesicles. The coat inner shell recruits the Sec13p-Sec31p complex, leading to coat polymerization and vesicle budding. Recent studies revealed that the Sec23p subunit sequentially interacts with three different binding partners to direct a COPII vesicle to the Golgi. One of these binding partners is the serine/threonine kinase Hrr25p. Hrr25p phosphorylates the COPII coat, driving the membrane-bound pool into the cytosol. The phosphorylated coat cannot rebind to the ER to initiate a new round of vesicle budding unless it is dephosphorylated. Here we screen all known protein phosphatases in yeast to identify one whose loss of function alters the cellular distribution of COPII coat subunits. This screen identifies the PP2A-like phosphatase Sit4p as a regulator of COPII coat dephosphorylation. Hyperphosphorylated coat subunits accumulate in the sit4Δ mutant in vivo. In vitro, Sit4p dephosphorylates COPII coat subunits. Consistent with a role in coat recycling, Sit4p and its mammalian orthologue, PP6, regulate traffic from the ER to the Golgi complex.

| S-EPMC3756924 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data