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

Various aspects of the biogenetic mechanisms that are involved in the insertion of nascent plasma membrane proteins into the endoplasmic reticulum (ER) membrane and their subsequent distribution through the cell have been investigated. For these studies chimeric genes that encode hybrid proteins containing carboxy-terminal portions of the influenza virus hemagglutinin (154 amino acids) or the vesicular stomatitis virus envelope glycoprotein (G) (60 amino acids) linked to the carboxy terminus of a nearly complete secretory polypeptide, growth hormone (GH), were used. In in vitro transcription-translation experiments, it was found that the insertion signal in the GH portion of the chimeras led to incorporation of the membrane protein segments into the ER membrane. Effectively, GH became part of the luminal segment of membrane proteins of which only very small segments, corresponding to the cytoplasmic portions of the G or HA proteins, remained exposed on the surface of the microsomes. When the chimeric genes were expressed in transfected cells, the products, as expected, failed to be secreted and remained cell-associated. These results support the assignment of a halt transfer role to segments of the membrane polypeptides that include their transmembrane portions. The hybrid polypeptide containing the carboxy-terminal portion of HA linked to GH accumulated in a juxtanuclear region of the cytoplasm within modified ER cisternae, closely apposed to the Golgi apparatus. The location and appearance of these cisternae suggested that they represent overdeveloped transitional ER elements and thus may correspond to a natural way station between the ER and the Golgi apparatus, in which further transfer of the artificial molecules is halted. The GH-G hybrid could only be detected in transfected cells treated with chloroquine, a drug that led to its accumulation in the membranes of endosome or lysosome-like cytoplasmic vesicles. Although the possibility that the chimeric protein entered such vesicles directly from the Golgi apparatus cannot be ruled out, it appears more likely that it was first transferred to the cell surface and was then internalized by endocytosis.
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PMID:Biosynthesis and intracellular sorting of growth hormone-viral envelope glycoprotein hybrids. 299 6

Newly synthesized G protein of vesicular stomatitis virus is not transported to the surface of cultured mammalian cells during mitosis (Warren et al., 1983, J. Cell Biol. 97:1623-1628). To determine where intracellular transport is inhibited, we have examined the post-translational modifications of G protein, which are indicators of specific compartments on the transport pathway. G protein in mitotic cells had only endo H-sensitive oligosaccharides containing seven or eight mannose residues, but no terminal glucose, and was not fatty acylated. These modifications were indicative of processing only by enzymes of the endoplasmic reticulum (ER). Quantitative immunocytochemistry was used as an independent method to confirm that transport of G protein out of the ER was inhibited. The density of G protein in the ER cisternae was 2.5 times greater than in infected G1 cells treated similarly. Incubation of infected mitotic cells with cycloheximide, which inhibits protein synthesis without affecting transport, did not result in a decrease in the density of G protein in the ER cisternae, demonstrating that G protein cannot be chased out of the ER. These results suggest that intracellular transport stops at or before the first vesicle-mediated step on the pathway.
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PMID:Newly synthesized G protein of vesicular stomatitis virus is not transported to the Golgi complex in mitotic cells. 299 58

Polyclonal and monoclonal antibodies were raised against a synthetic peptide containing the 15 carboxy-terminal amino acids (497-511) of vesicular stomatitis virus glycoprotein (VSV-G). The polyclonal antibodies (alpha P4) reacted with epitopes distributed along the 15-residue peptide, whereas the monoclonal antibody (P5D4) reacted with one epitope containing the five carboxy-terminal amino acids. Both types of antibodies recognized the cytoplasmic domain of VSV-G synthesized by tissue culture cells infected with the temperature-sensitive 045-VSV mutant (ts045-VSV). They recognized immature forms of VSV-G in the rough endoplasmic reticulum (RER) and Golgi complex, as well as mature VSV-G at the cell surface and in budding virus. The effect of these antibodies on intracellular transport and maturation of VSV-G was studied by microinjection. Both divalent antibodies (alpha P4 and P5D4) blocked transport of VSV-G to the cell surface. Monovalent Fab' fragments of alpha P4 (alpha P4-Fabs) also interfered with the appearance of VSV-G at the cell surface; Fab fragments of P5D4 (P5D4-Fabs), however, had no inhibitory effect. These results suggest that accessibility of a cytoplasmic domain, located within the sequence of amino acids 497-506 of the carboxy-terminal tail, is essential for transport of VSV-G to the cell surface.
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PMID:Microinjected antibodies against the cytoplasmic domain of vesicular stomatitis virus glycoprotein block its transport to the cell surface. 301 26

Reexamination of the viral products of tsO45, a glycoprotein mutant of vesicular stomatitis virus, showed that at 39 degrees C there was a conversion of the glycoprotein (G) to a truncated, soluble form, Gs, which subsequently appeared in the extracellular medium. The half-life for this intracellular conversion and extracellular appearance was about 2 h at 39 degrees C. Gs was precipitated by a monoclonal antibody to the ektodomain but not by an antipeptide serum made against the first 15 amino acids at the carboxy terminus of G. Gs was also resistant to endoglycosidase H digestion. On the basis of pulse-chase experiments, the generation of Gs most probably occurred in the rough endoplasmic reticulum. This additional phenotype of the tsO45 mutant provides another approach for studying the generation and subsequent transport of a secreted protein in fibroblast cells.
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PMID:Further characterization of the vesicular stomatitis virus temperature-sensitive O45 mutant: intracellular conversion of the glycoprotein to a soluble form. 301 92

Saccharomyces cerevisiae strains transformed with plasmids containing cDNAs coding for the glycoproteins of vesicular stomatitis or Sindbis viruses can be induced to produce large amounts of glycosylated virus glycoproteins. Studies reported here show that these proteins from high molecular weight disulfide-linked oligomers in the yeast endoplasmic reticulum. Oligomers were also found for two genetically altered forms of VSV G; one of these was lacking the membrane anchor domain and the other had the cysteine in the cytoplasmic tail replaced with serine. These oligomers can be separated from the bulk of yeast proteins by brief high-speed centrifugation of yeast extracts prepared by boiling cells with 1% sodium dodecyl sulfate. Treatment with thiol-reducing agents converts the oligomers to soluble monomeric forms, and this procedure leads to a substantial purification of glycoproteins from bulk yeast protein.
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PMID:Expression of genes encoding vesicular stomatitis and Sindbis virus glycoproteins in yeast leads to formation of disulfide-linked oligomers. 301 85

Virus particles, lacking the spike G-glycoproteins, are produced during infection of Vero cells with the vesicular stomatitis virus mutant ts045 at the restrictive temperature 39.5 degrees C. At this temperature the mutated G proteins are blocked in their intracellular transport in the endoplasmic reticulum. We have studied the role of the G proteins in the formation of these spikeless virus particles. The results showed that the spikeless particles contain a full complement of membrane anchors, derived from the carboxy-terminal end of the G protein. Our observations suggest that virus particles are formed at the restrictive temperature with G protein which is later cleaved to produce spikeless particles. We suggest that this is due to a leak of G protein to the cell surface at 39.5 degrees C where budding then takes place, presumably driven by a G protein C-terminal tail--nucleocapsid interaction.
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PMID:The budding mechanism of spikeless vesicular stomatitis virus particles. 301 69

The temperature and ATP dependence of transport of the vesicular stomatitis virus strain ts045 G protein from the endoplasmic reticulum (ER) to an early Golgi compartment containing mannosidase I was studied in the mutant Chinese hamster ovary cell clone 15B. Appearance of G protein containing the Man5GlcNAc2 oligosaccharide species occurred after a shift to the permissive temperature with a lag period of 5 min and without detectable formation of the intermediate Man7GlcNAc2 and Man6GlcNAc2 species. Two biochemically distinct transport steps were detected during transport from the ER to the Golgi. An initial step is temperature sensitive, thermoreversible, and requires a high threshold of cellular ATP for maximal rate of transport (80% of the normal cellular ATP pool). Export from the ER is inhibited at 65% of the normal cellular ATP pool. Prolonged incubation at reduced levels of cellular ATP or at the restrictive temperature resulted in the accumulation of G protein in either the Man8GlcNAc2 species or the Man7GlcNAc2 and Man6GlcNAc2 species, respectively. Reversal of the temperature-sensitive block is ATP coupled. A second step is insensitive to incubation at the restrictive temperature and proceeds efficiently when the cellular ATP pool is reduced to 20% of the control. G protein accumulates at this intermediate step during prolonged incubation at 15 degrees C. The data suggest a functional division of processes required for transport of protein between the ER and Golgi compartments. The two steps may reflect the export (budding) and delivery (fusion) of proteins through vesicular trafficking between the ER and Golgi.
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PMID:ATP-coupled transport of vesicular stomatitis virus G protein between the endoplasmic reticulum and the Golgi. 302 50

The oligosaccharide processing intermediates of the vesicular stomatitis virus strain ts045 G protein were used to identify ATP- and temperature-sensitive steps in the constitutive pathway of protein transfer to the cell surface. In addition to the initial ATP-sensitive step required for export from the endoplasmic reticulum (Balch, W. E., Elliott, M. M., and Keller, D. S. (1986) J. Biol. Chem. 261, 14681-14689), two distinct ATP-sensitive steps functionally dissect the Golgi into at least 3 compartments: a cis compartment containing the trimming enzyme mannosidase I, a medial compartment conferring resistance to endoglycosidase H, and a trans compartment containing terminal glycosyl transferases. A fourth ATP-sensitive step is required for export of G protein from the trans Golgi to the cell surface. A high threshold of cellular ATP (70% of the control) was required for maximal rates of transport between Golgi compartments. Transport between compartments is inhibited at 40% of the normal cellular ATP pool. Only a single temperature-sensitive step localized to the endoplasmic reticulum inhibited transport of ts045 G protein to the cell surface. The data suggest that ATP-sensitive steps punctuate transport of protein between compartmental boundaries of the secretory pathway.
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PMID:ATP-coupled transport of vesicular stomatitis virus G protein. Functional boundaries of secretory compartments. 302 51

Transport of the vesicular stomatitis virus-encoded glycoprotein (G protein) between the endoplasmic reticulum (ER) and the cis Golgi compartment has been reconstituted in a cell-free system. Transfer is measured by the processing of the high mannose (man GlcNAc2) ER form of G protein to the man5GlcNAc5 form by the cis Golgi enzyme alpha-mannosidase I. G protein is rapidly and efficiently transported to the Golgi complex by a process resembling that observed in vivo. G protein is trimmed from the high mannose form to the man5GlcNAc2 form without the appearance of the intermediate man GlcNAc2 oligosaccharide species, as is observed in vivo. G protein is found in a sealed membrane-bound compartment before and after incubation. Processing in vitro is sensitive to detergent, and the Golgi alpha-mannosidase I inhibitor 1-deoxymannorjirimycin. Transport between the ER and Golgi complex in vitro requires the addition of a high speed supernatant (cytosol) of cell homogenates, and requires energy in the form of ATP. Efficient reconstitution of export of protein from the ER requires the preparation of homogenates from mitotic cell populations in which the nuclear envelope, ER, and Golgi compartments have been physiologically disassembled before cell homogenization. These results suggest that the high efficiency of transport observed here may require reassembly of functional organelles in vitro.
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PMID:Reconstitution of transport of vesicular stomatitis virus G protein from the endoplasmic reticulum to the Golgi complex using a cell-free system. 302 44

cDNA fusions were employed to construct a 35-kDa hybrid protein bearing the amino-terminal signal sequence of pre-ornithine carbamoyltransferase (pOCT), a mitochondrial matrix enzyme, fused to the carboxyl-terminal half of vesicular stomatitis virus G protein (VSV G). Following transcription-translation in vitro, the hybrid protein was imported by purified mitochondria and processed at its amino terminus by the matrix processing enzyme. The protein, however, remained anchored in the mitochondrial inner membrane, apparently in a transmembrane configuration, via the hydrophobic VSV G stop-transfer domain; a small portion (approximately 2 kDa) of the G protein fragment was accessible to protease digestion only after selective permeabilization of the mitochondrial outer membrane with digitonin, a finding consistent with localization of the extreme carboxyl-terminal cytoplasmic tail of G in the intermembrane space. The results demonstrate that the membrane-anchor domain of VSV G can function in a post-translational manner and can operate in membranes other than those derived from the endoplasmic reticulum. However, it appears to be selectively recognized as a stop-transfer signal by the translocation machinery of the mitochondrial inner, rather than outer, membrane.
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PMID:Import of hybrid vesicular stomatitis G protein to the mitochondrial inner membrane. 303 Oct 55


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