scholarly journals Exit of newly synthesized membrane proteins from the trans cisterna of the Golgi complex to the plasma membrane.

1985 ◽  
Vol 101 (3) ◽  
pp. 949-964 ◽  
Author(s):  
G Griffiths ◽  
S Pfeiffer ◽  
K Simons ◽  
K Matlin

The intracellular location at which the G protein of vesicular stomatitis virus accumulated when transport was blocked at 20 degrees C has been studied by biochemical, cytochemical, and immunocytochemical methods. Our results indicated that the viral G protein was blocked in that cisterna of the Golgi stack which stained for acid phosphatase. At 20 degrees C this trans cisterna became structurally altered by the accumulation of G protein. This alteration was characterized by extensive areas of membrane buds which were covered by a cytoplasmic coat. These coated structures were of two kinds--those that labeled with anti-clathrin antibodies and those that did not. The clathrin-coated pits consistently did not label with anti-G antibodies. Upon warming infected cells to 32 degrees C, G protein appeared on the surface within minutes. Concomitantly, the trans cisterna lost its characteristic structural organization. Double-labeling experiments were performed in which G protein localization was combined with staining for horseradish peroxidase, which had been taken up from the extracellular medium by endocytosis. The results suggest that the trans cisterna was distinct from the endosome compartment and that the latter was not an obligatory station in the route taken by G protein to the cell surface.

1994 ◽  
Vol 5 (2) ◽  
pp. 99-104 ◽  
Author(s):  
M. J. Almela ◽  
A. Irurzun ◽  
L. Carrasco

The naturally occurring isoflavonoid orobol exhibits antiviral effects against some animal viruses. Addition of the compound after virus entry inhibits the appearance of late viral protein synthesis in Vesicular Stomatitis Virus, influenza, or vaccinia virus-infected cells, but has no effect on poliovirus protein synthesis. Concentrations of the compound above 10–50 Mg ml−1 are sufficient to decrease the synthesis of VSV proteins when added early during infection, but have no effect on viral translation if added later, indicating that orobol does not block VSV translation directly. The synthesis of VSV nucleic acids is one of the targets of this flavonoid. The synthesis of both minus and plus-stranded viral RNA are inhibited by orobol when added during the first 2 h of infection. In addition, this compound interferes potently with the glycosylation of VSV G protein, indicating that orobol has several targets of antiviral action. The possibility that orobol interferes with the function of the cellular vesicular system is discussed.


1984 ◽  
Vol 99 (1) ◽  
pp. 260-271 ◽  
Author(s):  
J E Rothman ◽  
R L Miller ◽  
L J Urbani

The transfer of the vesicular stomatitis virus-encoded glycoprotein (G protein) between Golgi populations in fused cells (Rothman, J. E., L. J. Urbani, and R. Brands. 1984. J. Cell Biol. 99:248-259) is exploited here to study and to help define the compartmental organization of the Golgi stack and to characterize the mechanism of intercompartmental transport. We find that G protein that has just received its peripheral N-acetylglucosamine in the Golgi complex of one cell is efficiently transferred to the Golgi complex of another cell to receive galactose (Gal). Remarkably, this transport occurs at the same rate between these two compartments whether they are present in the same or different Golgi populations. Therefore, a dissociative (presumably vesicular) transport step moves G protein from one part of the Golgi in which N-acetylglucosamine is added to another in which Gal is added. Minutes later, upon receiving Gal, the same G protein molecules are very poorly transferred to an exogenous Golgi population after cell fusion. Therefore, once this intercompartmental transfer has already taken place (before fusion), it cannot take place again (after fusion); i.e., transport across the compartment boundary in the Golgi complex that separates the sites of N-acetylglucosamine and Gal incorporation is a vectorial process. We conclude that transfers between Golgi cisternae occur by a stochastic process in which transport vesicles budding from cisternae dissociate, can diffuse away, and then attach to and fuse with the appropriate target cisterna residing in the same or in a different stack, based on a biochemical pairing after a random encounter. Under these circumstances, a transported protein would almost always randomize among stacks with each intercisternal transfer; it would not progress systematically through a single stack. Altogether, our studies define three sequential compartments in the Golgi stack.


1989 ◽  
Vol 108 (3) ◽  
pp. 811-819 ◽  
Author(s):  
K Suh ◽  
J E Bergmann ◽  
C A Gabel

Cells infected with a temperature-sensitive mutant of vesicular stomatitis virus, ts045, or transfected with the plasmid vector pdTM12 produce mutant forms of the G protein that remain within the ER. The mutant G proteins were isolated by immunoprecipitation from cells metabolically labeled with [2-3H]mannose to facilitate analysis of the protein-linked oligosaccharides. The 3H-labeled glycopeptides recovered from the immunoprecipitated G proteins contained high mannose-type oligosaccharides. Structural analysis, however, indicated that 60-78% of the 3H-mannose-labeled oligosaccharides contained a single glucose residue and no fewer than eight mannose residues. The 3H-labeled ts045 oligosaccharides were deglucosylated and processed to complex-type units after the infected cells were returned to the permissive temperature. When shifted to the permissive temperature in the presence of a proton ionophore, the G protein oligosaccharides were deglucosylated but remained as high mannose-type units. The glucosylated state was observed, therefore, when the G protein existed in an altered conformation. The ts045 G protein oligosaccharides were deglucosylated in vitro by glucosidase II at both the permissive and nonpermissive temperatures. G protein isolated from ts045-infected cells labeled with [6-3H]galactose in the presence of cycloheximide contained 3H-glucose-labeled monoglucosylated oligosaccharides, indicating that the high mannose oligosaccharides were glucosylated in a posttranslational process. These results suggest that aberrant G proteins are selectively modified by resident ER enzymes to retain monoglucosylated oligosaccharides.


1988 ◽  
Vol 107 (5) ◽  
pp. 1707-1715 ◽  
Author(s):  
J E Bergmann ◽  
P J Fusco

Using monoclonal antibodies and indirect immunofluorescence microscopy, we investigated the distribution of the M protein in situ in vesicular stomatitis virus-(VSV) infected MDCK cells. M protein was observed free in the cytoplasm and associated with the plasma membrane. Using the ts045 mutant of VSV to uncouple the synthesis and transport of the VSV G protein we demonstrated that this distribution was not related to the presence of G protein on the cell surface. Sections of epon-embedded infected cells labeled with antibody to the M protein and processed for indirect horseradish peroxidase immunocytochemistry revealed that the M protein was associated specifically with the basolateral plasma membrane. The G and M proteins of VSV have therefore evolved features which bring them independently to the basolateral membrane of polarized epithelial cells and allow virus to bud specifically from that membrane.


1989 ◽  
Vol 92 (4) ◽  
pp. 643-654
Author(s):  
J.K. Burkhardt ◽  
S. Hester ◽  
Y. Argon

The post-translational modifications of the G protein of vesicular stomatitis virus, described in the preceding paper, indicate that its transport is arrested by carbonylcyanide m-chlorophenylhydrazone (CCCP) in or near the trans-Golgi. Immunofluorescence microscopy of BHK-21 cells infected with vesicular stomatitis virus and treated with CCCP shows an accumulation of G protein in the Golgi area. In the same cells, the morphology of wheat germ agglutinin (WGA)-staining structures in the perinuclear region is aberrant. Using anti-BiP antibody, there is no obvious change in the structure of the endoplasmic reticulum. Electron microscopy reveals that the aberrant structures in the perinuclear region result from dilation of Golgi cisternae and accumulation of large vacuoles near the Golgi stack. The appearance of these aberrant structures is dose-dependent and they disappear after the protonophore is removed. The vast majority of the vacuoles accumulate on the trans side of the Golgi stack. A small fraction of them contain the marker enzyme thiamine pyrophosphatase (TPPase). By immunoelectron microscopy, most of the vacuoles contain G protein. We conclude that most of the Golgi-associated vacuoles are derived from a distal Golgi transport compartment, possibly the trans-Golgi reticulum, and that CCCP reversibly inhibits the transport of newly synthesized G protein through this distal compartment.


2003 ◽  
Vol 77 (7) ◽  
pp. 3985-3992 ◽  
Author(s):  
Erica L. Brown ◽  
Douglas S. Lyles

ABSTRACT The glycoprotein (G protein) of vesicular stomatitis virus (VSV) is primarily organized in plasma membranes of infected cells into membrane microdomains with diameters of 100 to 150 nm, with smaller amounts organized into microdomains of larger sizes. This organization has been observed in areas of the infected-cell plasma membrane that are outside of virus budding sites as well as in the envelopes of budding virions. These observations raise the question of whether the intracellular virion components play a role in organizing the G protein into membrane microdomains. Immunogold-labeling electron microscopy was used to analyze the distribution of the G protein in arbitrarily chosen areas of plasma membranes of transfected cells that expressed the G protein in the absence of other viral components. Similar to the results with virus-infected cells, the G protein was organized predominantly into membrane microdomains with diameters of approximately 100 to 150 nm. These results indicate that internal virion components are not required to concentrate the G protein into membrane microdomains with a density similar to that of virus envelopes. To determine if interactions between the G protein cytoplasmic domain and internal virion components were required to create a virus budding site, cells infected with recombinant VSVs encoding truncation mutations of the G protein cytoplasmic domain were analyzed by immunogold-labeling electron microscopy. Deletion of the cytoplasmic domain of the G protein did not alter its partitioning into the 100- to 150-nm microdomains, nor did it affect the incorporation of the G protein into virus envelopes. These data support a model for virus assembly in which the G protein has the inherent property of partitioning into membrane microdomains that then serve as the sites of assembly of internal virion components.


1979 ◽  
Vol 80 (2) ◽  
pp. 416-426 ◽  
Author(s):  
F N Katz ◽  
H F Lodish

Previous work has shown that the mRNA encoding the vesicular stomatitis virus (VSV) glycoprotein (G) is bound to the rough endoplasmic reticulum (RER) and that newly made G protein is localized to the RER. In this paper, we have investigated the topology and processing of the newly synthesized G protein in microsomal vesicles. G was labeled with [35S]methionine ([35S]met), either by pulse-labeling infected cells or by allowing membrane-bound polysomes containing nascent G polipeptides to complete G synthesis in vitro. In either case, digestion of microsomal vesicles with any of several proteases removes approximately 5% (30 amino acids) from each G molecule. These proteases will digest the entire G protein if detergents are present during digestion. Using the method of Dintzis (1961, Proc. Natl. Acad. Sci. U. S. A. 47:247--261) to order tryptic peptides (8), we show that peptides lost from G protein by protease treatment of closed vesicles are derived from the carboxyterminus of the molecule. The newly made VSV G in microsomal membranes is glycosylated. If carbohydrate is removed by glycosidases, the resultant peptide migrates more rapidly on polyacrylamide gels than the unglycosylated, G0, form synthesized in cell-free systems in the absence of membranes. We infer that some proteolytic cleavage of the polypeptide backbone is associated with membrane insertion of G. Further, our findings demonstrate that, soon after synthesis, G is found in a transmembrane, asymmetric orientation in microsomal membranes, with its carboxyterminus exposed to the extracisternal, or cytoplasmic, face of the vesicles, and with most or all of its amino-terminal peptides and its carbohydrate sequestered within the bilayer and lumen of the microsomes.


1982 ◽  
Vol 94 (1) ◽  
pp. 36-41 ◽  
Author(s):  
J J Bergeron ◽  
G J Kotwal ◽  
G Levine ◽  
P Bilan ◽  
R Rachubinski ◽  
...  

The intracellular migration of G protein in vesicular stomatitis virus-infected cells was visualized by light and electron microscope radioautography after a 2-min pulse with [3H]mannose followed by nonradioactive chase for various intervals. The radioactivity initially (at 5-10 min) appeared predominantly in the endoplasmic reticulum, and the [3H]mannose-labeled G protein produced was sensitive to endoglycosidase H. Silver grains were subsequently (at 30-40 min) observed over the Golgi apparatus, and the [3H]mannose-labeled G protein became resistant to endoglycosidase H digestion. Our data directly demonstrate the intracellular transport of a plasmalemma-destined transmembrane glycoprotein through the Golgi apparatus.


1980 ◽  
Vol 33 (1) ◽  
pp. 411-422 ◽  
Author(s):  
F Wyers ◽  
C Richard-Molard ◽  
D Blondel ◽  
S Dezelee

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