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Query: UMLS:C0038362 (stomatitis)
 8,852 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The glycoside digitonin was used to selectively permeabilize the plasma membrane exposing functionally and morphologically intact ER and Golgi compartments. Permeabilized cells efficiently transported vesicular stomatitis virus glycoprotein (VSV-G) through sealed, membrane-bound compartments in an ATP and cytosol dependent fashion. Transport was vectorial. VSV-G protein was first transported to punctate structures which colocalized with p58 (a putative marker for peripheral punctate pre-Golgi intermediates and the cis-Golgi network) before delivery to the medial Golgi compartments containing alpha-1,2-mannosidase II and processing of VSV-G to endoglycosidase H resistant forms. Exit from the ER was inhibited by an antibody recognizing the carboxyl-terminus of VSV-G. In contrast, VSV-G protein colocalized with p58 in the absence of Ca2+ or the presence of an antibody which inhibits the transport component NSF (SEC18). These studies demonstrate that digitonin permeabilized cells can be used to efficiently reconstitute the early secretory pathway in vitro, allowing a direct comparison of the morphological and biochemical events involved in vesicular tafficking, and identifying a key role for the p58 containing compartment in ER to Golgi transport.
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PMID:Morphological analysis of protein transport from the ER to Golgi membranes in digitonin-permeabilized cells: role of the P58 containing compartment. 144 90

COPI and COPII are vesicle coat complexes whose assembly is regulated by the ARF1 and Sar1 GTPases, respectively. We show that COPI and COPII coat complexes are recruited separately and independently to ER (COPII), pre-Golgi (COPI, COPII), and Golgi (COPI) membranes of mammalian cells. To address their individual roles in ER to Golgi transport, we used stage specific in vitro transport assays to synchronize movement of cargo to and from pre-Golgi intermediates, and GDP- and GTP-restricted forms of Sar1 and ARF1 proteins to control coat recruitment. We find that COPII is solely responsible for export from the ER, is lost rapidly following vesicle budding and mediates a vesicular step required for the build-up of pre-Golgi intermediates composed of clusters of vesicles and small tubular elements. COPI is recruited onto pre-Golgi intermediates where it initiates segregation of the anterograde transported protein vesicular stomatitis virus glycoprotein (VSV-G) from the retrograde transported protein p58, a protein which actively recycles between the ER and pre-Golgi intermediates. We propose that sequential coupling between COPII and COPI coats is essential to coordinate and direct bi-directional vesicular traffic between the ER and pre-Golgi intermediates involved in transport of protein to the Golgi complex.
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PMID:Sequential coupling between COPII and COPI vesicle coats in endoplasmic reticulum to Golgi transport. 749 Feb 91

ER to Golgi transport requires the function of two distinct vesicle coat complexes, termed COPI (coatomer) and COPII, whose assembly is regulated by the small GTPases ADP-ribosylation factor 1 (ARF1) and Sar1, respectively. To address their individual roles in transport, we have developed a new assay using mammalian microsomes that reconstitute the formation of ER-derived vesicular carriers. Vesicles released from the ER were found to contain the cargo molecule vesicular stomatitis virus glycoprotein (VSV-G) and p58, an endogenous protein that continuously recycles between the ER and pre-Golgi intermediates. Cargo was efficiently sorted from resident ER proteins during vesicle formation in vitro. Export of VSV-G and p58 were found to be exclusively mediated by COPII. Subsequent movement of ER-derived carriers to the Golgi stack was blocked by a trans-dominant ARF1 mutant restricted to the GDP-bound state, which is known to prevent COPI recruitment. To establish the initial site of coatomer assembly after export from the ER, we immunoisolated the vesicular intermediates and tested their ability to recruit COPI. Vesicles bound coatomer in a physiological fashion requiring an ARF1-guanine nucleotide exchange activity. These results suggest that coat exchange is an early event preceding the targeting of ER-derived vesicles to pre-Golgi intermediates.
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PMID:COPII vesicles derived from mammalian endoplasmic reticulum microsomes recruit COPI. 892 75

p53/58 is a transmembrane protein that continuously recycles between the ER and pre-Golgi intermediates composed of vesicular-tubular clusters (VTCs) found in the cell periphery and at the cis face of the Golgi complex. We have generated an antibody that uniquely recognizes the p53/58 cytoplasmic tail. Here we present evidence that this antibody arrests the anterograde transport of vesicular stomatitis virus glycoprotein and leads to the accumulation of p58 in pre-Golgi intermediates. Consistent with a role for the KKXX retrieval motif found at the cytoplasmic carboxyl terminus of p53/58 in retrograde traffic, inhibition of transport through VTCs correlates with the ability of the antibody to block recruitment of COPI coats to the p53/58 cytoplasmic tail and to p53/58-containing membranes. We suggest that p53/58 function may be required for the coupled exchange of COPII for COPI coats during segregation of anterograde and retrograde transported proteins.
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PMID:p53/58 binds COPI and is required for selective transport through the early secretory pathway. 915 66

The COPII coat complex found on endoplasmic reticulum (ER)-derived vesicles plays a critical role in cargo selection. We now address the potential role of biosynthetic cargo in modulating COPII coat assembly and vesicle budding. The ER accumulation of vesicular stomatitis glycoprotein (VSV-G), a transmembrane protein, or the soluble PiZ variant of alpha1-antitrypsin, reduced levels of general COPII vesicle formation in vivo. Consistent with this result, conditions that prevent the export of VSV-G from the ER led to a significant inhibition of general COPII vesicle budding from ER microsomes and the export of an endogenous recycling protein p58 in vitro. In contrast, synchronized export of VSV-G stimulated COPII vesicle budding both in vivo and in vitro. Under conditions where VSV-G is retained in the ER, we find that it can to be recovered in pre-budding complexes containing COPII components. These results suggest that the export of biosynthetic cargo is integrated with ER functions involved in protein folding and oligomerization. The ability of biosynthetic cargo to prevent or enhance ER export suggests that interactions of cargo with the COPII machinery contribute to the formation of vesicles budding from the ER.
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PMID:Cargo can modulate COPII vesicle formation from the endoplasmic reticulum. 993 43

The small GTPase Rab2 requires atypical protein kinase C iota/lambda (PKCiota/lambda) kinase activity to promote vesicle budding from normal rat kidney cell microsomes (Tisdale, E. J. (2000) Traffic 1, 702-712). The released vesicles lack anterograde-directed cargo but contain coat protein I (COPI) and the recycling protein p53/p58, suggesting that the vesicles traffic in the retrograde pathway. In this study, we have directly characterized the role of PKCiota/lambda in the early secretory pathway. A peptide corresponding to the unique PKCiota/lambda pseudosubstrate domain was introduced into an in vitro assay that efficiently reconstitutes transport of vesicular stomatitis virus glycoprotein from the endoplasmic reticulum to the cis-medial Golgi compartments. This peptide blocked transport in a dose-dependent manner. Moreover, normal rat kidney cells incubated with Rab2 and the pseudosubstrate peptide displayed abundant swollen or dilated vesicles that contained Rab2, PKCiota/lambda, beta-COP, and p53/p58. Because Rab2, beta-COP, and p53/p58 are marker proteins for pre-Golgi intermediates (vesicular tubular clusters,VTCs), most probably the swollen vesicles are derived from VTCs. Similar results were obtained when the assays were supplemented with kinase-dead PKCiota/lambda (W274K). Both the pseudosubstrate peptide and kinase-dead PKCiota/lambda in tandem with Rab2 caused sustained membrane association of PKCiota/lambda, suggesting that reverse translocation was inhibited. Importantly, the inhibitory phenotype of kinase-dead PKCiota/lambda was reversed by PKCiota/lambda wild type. These combined results indicate that PKCiota/lambda is essential for protein transport in the early secretory pathway and suggest that PKCiota/lambda kinase activity is required to promote Rab2-mediated vesicle budding at a VTC subcompartment enriched in recycling cargo.
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PMID:Atypical protein kinase C plays a critical role in protein transport from pre-Golgi intermediates. 1287 60

The Golgi complex functions in transport of molecules from the endoplasmic reticulum (ER) to the plasma membrane and other distal organelles as well as in retrograde transport to the ER. The fungal metabolite brefeldin A (BFA) promotes dissociation of ADP-ribosylation-factor-1 (ARF1) and the coatomer protein complex-I (COP-I) from Golgi membranes, followed by Golgi tubulation and fusion with the ER. Here we demonstrate that the cationic ionophore monensin inhibited the BFA-mediated Golgi redistribution to the ER without interfering with ARF1 and COP-I dissociation. Preservation of a perinuclear Golgi despite COP-I and ARF1 dissociation enables addressing the involvement of these proteins in anterograde ER to Golgi transport. The thermo-reversible folding mutant of vesicular stomatitis virus G protein (VSVGtsO45) was retained in the ER in the presence of both monensin and BFA, thus supporting ARF1/COP-I participation in ER-exit processes. Live-cell imaging revealed that BFA-induced Golgi tubulation persisted longer in the presence of monensin, suggesting that monensin inhibits tubule fusion with the ER. Moreover, monensin also augmented Golgi-derived tubules that contained the ER-Golgi-intermediate compartment marker, p58, in the absence of BFA, signifying the generality of this effect. Taken together, we propose that monensin inhibits membrane fusion processes in the presence or absence of BFA.
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PMID:Uncoupling of brefeldin a-mediated coatomer protein complex-I dissociation from Golgi redistribution. 1610 82