scholarly journals Core Proteome and Architecture of COPI Vesicles

2018 ◽  
Author(s):  
Manuel Rhiel ◽  
Bernd Hessling ◽  
Qi Gao ◽  
Andrea Hellwig ◽  
Frank Adolf ◽  
...  
Keyword(s):  
Isotope Labeling ◽  
Protein Composition ◽  
Small Gtpase ◽  
Coated Vesicles ◽  
Coat Proteins ◽  
Intact Cells ◽  
Core Proteome ◽  
A Minor ◽  
Almost All

AbstractRetrieval of escaped ER-residents and intra-Golgi transport is facilitated by coat protein complex I (COPI)-coated vesicles. Their formation requires the activated small GTPase ADP-ribosylation factor (Arf) and the coat complex coatomer. Here we assess the protein composition of COPI vesicles by combining stable isotope labeling with amino acids in cell culture (SILAC) with in vitro reconstitution of COPI vesicles from semi-intact cells (SIC) using the minimal set of recombinant coat proteins. This approach yields an unbiased picture of the proteome of these carriers. We define a set of ~40 proteins common to COPI vesicles produced from different human as well as murine cell lines. Almost all bona fide COPI vesicle proteins are either ER-Golgi cycling proteins or Golgi-residents, while only a minor portion of secreted proteins was found. Moreover, we have investigated a putative role of γ- and ζ-COP as well as Arf isoforms in sorting and recruitment of specific proteins into COPI vesicles. As opposed to the related COPII system, all isoforms of coatomer and all COPI-forming isoforms of the small GTPase Arf produce COPI-coated vesicles with strikingly similar protein compositions. We present a model for the core architecture of COPI vesicles.

COPI vesicles accumulating in the presence of a GTP restricted arf1 mutant are depleted of anterograde and retrograde cargo

2000 ◽  
Vol 113 (1) ◽  
pp. 135-144 ◽  
Author(s):  
R. Pepperkok ◽  
J.A. Whitney ◽  
M. Gomez ◽  
T.E. Kreis
Keyword(s):  
Protein Transport ◽  
Ectopic Expression ◽  
Small Gtpase ◽  
Coated Vesicles ◽  
Gtp Hydrolysis ◽  
Rapid Accumulation ◽  
Gamma S

Microinjection of the slowly hydrolyzable GTP analogue GTP(gamma)S or the ectopic expression of a GTP restricted mutant of the small GTPase arf1 (arf1[Q71L]) leads to the rapid accumulation of COPI coated vesicles and buds in living cells. This effect is blocked at 15 degrees C and by microinjection of antibodies against (beta)-COP. Anterograde and retrograde membrane protein transport markers, which have been previously shown to be incorporated into COPI vesicles between the endoplasmic reticulum and Golgi complex, are depleted from the GTP(gamma)S or arf1[Q71L] induced COPI coated vesicles and buds. In contrast, in control cells 30 to 60% of the COPI carriers co-localize with these markers. These in vivo data corroborate recent in vitro work, suggesting that GTP(gamma)S and arf1[Q71L] interfere with the sorting of membrane proteins into Golgi derived COPI vesicles, and provide the first in vivo evidence for a role of GTP hydrolysis by arf1 in the sorting of cargo into COPI coated vesicles and buds.

Expression of auxilin or AP180 inhibits endocytosis by mislocalizing clathrin: evidence for formation of nascent pits containing AP1 or AP2 but not clathrin

2001 ◽  
Vol 114 (2) ◽  
pp. 353-365 ◽  
Author(s):  
X. Zhao ◽  
T. Greener ◽  
H. Al-Hasani ◽  
S.W. Cushman ◽  
E. Eisenberg ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cultured Cells ◽  
Coated Vesicles ◽  
Coated Pits ◽  
Trans Golgi Network ◽  
J Domain ◽  
Almost All ◽  
Golgi Network ◽  
Assembly Proteins

Although uncoating of clathrin-coated vesicles is a key event in clathrin-mediated endocytosis it is unclear what prevents uncoating of clathrin-coated pits before they pinch off to become clathrin-coated vesicles. We have shown that the J-domain proteins auxilin and GAK are required for uncoating by Hsc70 in vitro. In the present study, we expressed auxilin in cultured cells to determine if this would block endocytosis by causing premature uncoating of clathrin-coated pits. We found that expression of auxilin indeed inhibited endocytosis. However, expression of auxilin with its J-domain mutated so that it no longer interacted with Hsc70 also inhibited endocytosis as did expression of the clathrin-assembly protein, AP180, or its clathrin-binding domain. Accompanying this inhibition, we observed a marked decrease in clathrin associated with the plasma membrane and the trans-Golgi network, which provided us with an opportunity to determine whether the absence of clathrin from clathrin-coated pits affected the distribution of the clathrin assembly proteins AP1 and AP2. Surprisingly we found almost no change in the association of AP2 and AP1 with the plasma membrane and the trans-Golgi network, respectively. This was particularly obvious when auxilin or GAK was expressed with functional J-domains since, in these cases, almost all of the clathrin was sequestered in granules that also contained Hsc70 and auxilin or GAK. We conclude that expression of clathrin-binding proteins inhibits clathrin-mediated endocytosis by sequestering clathrin so that it is no longer available to bind to nascent pits but that assembly proteins bind to these pits independently of clathrin.

scholarly journals Multivariate proteomic profiling identifies novel accessory proteins of coated vesicles

2012 ◽  
Vol 197 (1) ◽  
pp. 141-160 ◽  
Author(s):  
Georg H.H. Borner ◽  
Robin Antrobus ◽  
Jennifer Hirst ◽  
Gary S. Bhumbra ◽  
Patrycja Kozik ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Isotope Labeling ◽  
Principal Component ◽  
Coated Vesicles ◽  
Coated Vesicle ◽  
Coat Proteins ◽  
Proteomic Profiling ◽  
Transport Vesicles ◽  
Associated Proteins ◽  
Sirna Knockdown

Despite recent advances in mass spectrometry, proteomic characterization of transport vesicles remains challenging. Here, we describe a multivariate proteomics approach to analyzing clathrin-coated vesicles (CCVs) from HeLa cells. siRNA knockdown of coat components and different fractionation protocols were used to obtain modified coated vesicle-enriched fractions, which were compared by stable isotope labeling of amino acids in cell culture (SILAC)-based quantitative mass spectrometry. 10 datasets were combined through principal component analysis into a “profiling” cluster analysis. Overall, 136 CCV-associated proteins were predicted, including 36 new proteins. The method identified >93% of established CCV coat proteins and assigned >91% correctly to intracellular or endocytic CCVs. Furthermore, the profiling analysis extends to less well characterized types of coated vesicles, and we identify and characterize the first AP-4 accessory protein, which we have named tepsin. Finally, our data explain how sequestration of TACC3 in cytosolic clathrin cages causes the severe mitotic defects observed in auxilin-depleted cells. The profiling approach can be adapted to address related cell and systems biological questions.

scholarly journals Interaction of SNAREs with ArfGAPs Precedes Recruitment of Sec18p/NSF

2007 ◽  
Vol 18 (8) ◽  
pp. 2852-2863 ◽  
Author(s):  
Christina Schindler ◽  
Anne Spang
Keyword(s):  
Conformational Change ◽  
Atp Hydrolysis ◽  
Small Gtpase ◽  
Snare Complex ◽  
Coat Proteins ◽  
Attachment Protein ◽  
Protein Receptor ◽  
Sensitive Factor ◽  
Target Membrane

Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins are key components of the fusion machinery in vesicular transport and in homotypic membrane fusion. We previously found that ADP-ribosylation factor GTPase activating proteins (ArfGAPs) promoted a conformational change on SNAREs that allowed recruitment of the small GTPase Arf1p in stoichiometric amounts. Here, we show that the ArfGAP Gcs1p accelerates vesicle (v)-target membrane (t)-SNARE complex formation in vitro, indicating that ArfGAPs may act as folding chaperones. These SNARE complexes were resolved in the presence of ATP by the yeast homologues of α-soluble N-ethylmaleimide-sensitive factor attachment protein and N-ethylmaleimide-sensitive factor, Sec17p and Sec18p, respectively. In addition, Sec18p and Sec17p also recognized the “activated” SNAREs even when they were not engaged in v-t-SNARE complexes. Here again, the induction of a conformational change by ArfGAPs was essential. Surprisingly, recruitment of Sec18p to SNAREs did not require Sec17p or ATP hydrolysis. Moreover, Sec18p displaced prebound Arf1p from SNAREs, indicating that Sec18p may have more than one function: first, to ensure that all vesicle coat proteins are removed from the SNAREs before the engagement in a trans-SNARE complex; and second, to resolve cis-SNARE complexes after fusion has occurred.

scholarly journals Endocytic vesicles and surface invaginations in cultured vascular endothelium: a morphometric comparison.

1981 ◽  
Vol 29 (12) ◽  
pp. 1437-1441 ◽  
Author(s):  
P F Davies ◽  
L Kuczera
Keyword(s):  
Cell Surface ◽  
Vascular Endothelium ◽  
Ruthenium Red ◽  
Coated Vesicles ◽  
Membrane Glycoproteins ◽  
Coated Pits ◽  
Ruthenium Red Staining ◽  
Almost All ◽  
Endocytic Vesicles

Ruthenium red staining of plasma membrane glycoproteins of confluent cultured arterial endothelial cells revealed that the limiting membrane of many apparently discrete cytoplasmic vesicles was continuous with the plasmalemma. Surface invaginations accessible to ruthenium red appeared as vesicles when sectioned out of the plane of attachment to the cell surface, Morphometric analysis of ruthenium red-positive (RR+) and ruthenium red-negative vesicles (RR-) indicated that 47.2% of the total apparent vesicle population was RR+ and that those infoldings accounted for 19.6 +/- 1.4% of the cell surface in transverse sections. Whereas 14.9% of the true vesicles (ruthenium red-negative) were coated vesicles, only 1.1% of RR+ "vesicles" were coated pits. These studies show that although many deep infoldings of the cell surface may be misinterpreted as vesicles, almost all are uncoated. The existence of discrete coated vesicles (independent of coated pits) in vascular endothelium in vitro is readily apparent.

scholarly journals Evidence that coated vesicles transport acetylcholine receptors to the surface membrane of chick myotubes.

1984 ◽  
Vol 98 (2) ◽  
pp. 498-506 ◽  
Author(s):  
S Bursztajn ◽  
G D Fischbach
Keyword(s):  
Acetylcholine Receptors ◽  
Prolonged Exposure ◽  
Addition Reaction ◽  
Surface Membrane ◽  
Coated Vesicles ◽  
Intact Cells ◽  
Saline Extract ◽  
Permeabilized Cells ◽  
Alpha Bungarotoxin

Coated vesicles are present in the myoplasm of embryonic chick myotubes grown in vitro. They are most numerous beneath regions of the surface membrane that contain a high density of acetylcholine receptors (AChR). Prolonged exposure of myotubes to saline extract of chick brain increases the number of intracellular AChR and the number of coated vesicles. This suggests that coated vesicles contain AChR, and this hypothesis was tested with horseradish peroxidase-alpha-bungarotoxin (HRP-alpha BTX) conjugates. The conjugates enter saponin-permeabilized cells and, as judged by the inhibition of [125I] alpha BTX binding, they label the entire intracellular AChR pool. Approximately 50% of the coated vesicles contained HRP-alpha BTX reaction product. In addition, reaction product was detected in Golgi cisternae and along membranes that bound a subsurface tubulovesicular network. The majority of labeled vesicles are probably involved in exocytosis rather than endocytosis of AChR because very few coated vesicles were labeled when HRP-alpha BTX was added to the medium bathing intact cells. Moreover, inhibition of protein synthesis with puromycin resulted in a large decrease in the number of labeled vesicles. These results suggest that a subpopulation of coated vesicles ferry newly synthesized AChR to the cell surface.

scholarly journals COPII-coated membranes function as transport carriers of intracellular procollagen-1

2017 ◽  
Author(s):  
Amita Gorur ◽  
Lin Yuan ◽  
Samuel J Kenny ◽  
Satoshi Baba ◽  
Ke Xu ◽  
...  
Keyword(s):  
Protein Complexes ◽  
Imaging Techniques ◽  
Coated Vesicles ◽  
Intact Cells ◽  
Vesicle Budding ◽  
Coated Membranes ◽  
Copii Vesicles ◽  
Optical Reconstruction

AbstractThe coat protein complex II (COPII) is essential for the secretion of large cargo, such as the 300 nm precursor fibrils of procollagen I (PC1). Previous work has shown that the CUL3-KLHL12 complex increases the size of COPII vesicles to over 300 nm in diameter and accelerates the secretion of PC1; however, the role of large COPII vesicles as PC1 transport carriers was not unambiguously demonstrated. In this study, using stochastic optical reconstruction microscopy (STORM), correlated light electron microscopy (CLEM), and live cell imaging we report the existence of mobile COPII-coated vesicles that completely encapsulate the cargo PC1 and are physically separated from ER. We have also developed a cell-free COPII vesicle budding reaction that reconstitutes the capture of PC1 into large COPII vesicles. This process requires COPII proteins and the GTPase activity of the COPII subunit SAR1. We conclude from in vivo and in vitro evidence that large COPII vesicles are bona fide carriers of PC1.SummaryCOPII may play a direct or indirect role in the traffic of large protein complexes such as procollagen. Using high resolution imaging techniques in intact cells and in vitro reconstituted vesicles, Gorur et al. show that COPII coated vesicles carry procollagen1.

scholarly journals ADP-ribosylation Factor 1-independent Protein Sorting and Export from thetrans-Golgi Network

2004 ◽  
Vol 279 (50) ◽  
pp. 52735-52743 ◽  
Author(s):  
Mark A. Ellis ◽  
Mark T. Miedel ◽  
Christopher J. Guerriero ◽  
Ora A. Weisz
Keyword(s):  
Small Gtpase ◽  
Proton Channel ◽  
Coat Proteins ◽  
Adp Ribosylation ◽  
Influenza Hemagglutinin ◽  
Intact Membrane ◽  
Golgi Network ◽  
Adp Ribosylation Factor

Polarized epithelial cells efficiently sort newly synthesized apical and basolateral proteins into distinct transport carriers that emerge from thetrans-Golgi network (TGN), and this sorting is recapitulated in nonpolarized cells. While the targeting signals of basolaterally destined proteins are generally cytoplasmically disposed, apical sorting signals are not typically accessible to the cytosol, and the transport machinery required for segregation and export of apical cargo remains largely unknown. Here we investigated the molecular requirements for TGN export of the apical marker influenza hemagglutinin (HA) in HeLa cells using anin vitroreconstitution assay. HA was released from the TGN in intact membrane-bound compartments, and export was dependent on addition of an ATP-regenerating system and exogenous cytosol. HA release was inhibited by guanosine 5′-O-(3-thiotriphosphate) (GTPγS) as well as under conditions known to negatively regulate apical transportin vivo, including expression of the acid-activated proton channel influenza M2. Interestingly, release of HA was unaffected by depletion of ADP-ribosylation factor 1, a small GTPase that has been implicated in the recruitment of all known adaptors and coat proteins to the Golgi complex. Furthermore, regulation of HA release by GTPγS or M2 expression was unaffected by cytosolic depletion of ADP-ribosylation factor 1, suggesting that HA sorting remains functionally intact in the absence of the small GTPase. These data suggest that TGN sorting and export of influenza HA does not require classical adaptors involved in the formation of other classes of exocytic carriers and thus appears to proceed via a novel mechanism.

Sex difference in histamine metabolism in the rat

1961 ◽  
Vol 201 (2) ◽  
pp. 224-226 ◽  
Author(s):  
K. J. Netter ◽  
V. H. Cohn ◽  
P. A. Shore
Keyword(s):  
Sex Difference ◽  
Diamine Oxidase ◽  
Female Rats ◽  
Male Rats ◽  
Metabolizing Enzymes ◽  
Methyl Transferase ◽  
Endogenous Histamine ◽  
A Minor ◽  
Almost All

Female rats excrete much more free endogenous histamine than do males. The sex difference lies in histamine catabolism rather than biosynthesis, since females excrete, unchanged, a much higher percentage of injected histamine than do males. Investigation of the activity in vitro of the major histamine metabolizing enzymes, diamine oxidase (DAO) and imidazol-N-methyl transferase (IMT), showed no sex difference in distribution or activity, nor was there a sex difference in the activity of liver methionine-activating enzyme. Measurement of the biologic half-life of injected histamine revealed no sex difference in normal rats, in rats treated with the DAO inhibitor, aminoguanidine (AG), or in rats after nephrectomy, which removes almost all of IMT activity. A combination of AG and nephrectomy, however, resulted in a marked sex difference, which did not appear to be due to histamine conjugation or to liver drug-metabolizing enzymes. The findings suggest that male rats possess a minor histamine-metabolizing pathway which females lack.

scholarly journals AP-2-containing clathrin coats assemble on mature lysosomes.

1996 ◽  
Vol 135 (6) ◽  
pp. 1801-1814 ◽  
Author(s):  
L M Traub ◽  
S I Bannykh ◽  
J E Rodel ◽  
M Aridor ◽  
W E Balch ◽  
...  
Keyword(s):  
Protein Trafficking ◽  
Coated Vesicle ◽  
Coat Proteins ◽  
Intracellular Protein ◽  
Temperature Dependent ◽  
Intact Cells ◽  
General Role ◽  
Absolute Requirement ◽  
Membrane Budding

Coat proteins appear to play a general role in intracellular protein trafficking by coordinating a membrane budding event with cargo selection. Here we show that the AP-2 adaptor, a clathrin-associated coat-protein complex that nucleates clathrin-coated vesicle formation at the cell surface, can also initiate the assembly of normal polyhedral clathrin coats on dense lysosomes under physiological conditions in vitro. Clathrin coat formation on lysosomes is temperature dependent, displays an absolute requirement for ATP, and occurs in both semi-intact cells and on purified lysosomes, suggesting that clathrin-coated vesicles might regulate retrograde membrane traffic out of the lysosomal compartment.

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