Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038362 (stomatitis)
 8,852 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Purified cores of vesicular stomatitis virus contain an enzymatic activity that converts GDP, UDP, and CDP into their corresponding triphosphates using ATP as the phosphate donor. Thus, the virion-associated RNA polymerase can synthesize mRNA normally in vitro even when one of the ribonucleoside triphosphates is replaced by its corresponding diphosphate. RNA synthesis does not proceed if ATP is replaced by ADP. Similarly RNA synthesis is impaired if CDP and UDP are present in the same reaction. The role of the nucleoside diphosphate kinase (NDP kinase, EC 2.7.4.6) in vesicular stomatitis virus mRNA synthesis in vitro is discussed.
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PMID:Nucleoside diphosphate kinase activity in purified cores of vesicular stomatitis virus. 22 22

A biochemical basis for the pea and lentil lectin resistance of two Chinese hamster ovary (CHO) cell mutants, Lec13 and Lec13A, was investigated. Studies of the G glycopeptides of vesicular stomatitis virus grown in the mutants indicated that Lec13 cells essentially lack the ability to add fucose to complex carbohydrates while Lec13A cells synthesize significant proportions of fucosylated, complex moieties. However, both mutants were known to be reverted to lectin sensitivity by growth in L-fucose, making them similar to the mouse lymphoma mutant, PLR1.3, which is defective in the conversion of GDP-mannose to GPD-fucose [M. L. Reitman, I. S. Trowbridge, and S. Kornfeld (1980) J. Biol. Chem. 255, 9900-9906]. Optimal conditions for the production of GDP-fucose from GDP-mannose by CHO cytosol were found to occur at pH 8 in the presence of 7.5 microM GDP-mannose, 15 mM Mg2+, 0.2 mM NAD+, 0.2 mM NADPH, 10 mM niacinamide, 5 mM ATP, and 50 mM Tris-HCl. Under these conditions, Lec13 cytosol produced no detectable GDP-fucose nor GDP-sugar intermediates while Lec13A cytosol produced significant quantities of both. Mixing experiments with Lec13 cytosol identified the first enzyme of the conversion pathway (GDP-mannose 4,6-dehydratase, EC 4.2.1.47) as the site of the block. In addition to being markedly reduced, the Lec13A 4,6-dehydratase activity was relatively insensitive to changes in pH in comparison to the activity in parental cytosol, suggesting that Lec13A cells might possess a structurally altered GDP-mannose 4,6-dehydratase enzyme.
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PMID:Two Chinese hamster ovary glycosylation mutants affected in the conversion of GDP-mannose to GDP-fucose. 242 10

The effect of phosphorylated ribavirin on a vesicular stomatitis virus (VSV) in vitro transcription reaction was examined. Viral mRNA synthesized in the presence of the 5' mono-, di-, and triphosphorylated forms of the drug translated with equal efficiencies under the test conditions. However, all three phosphorylated species inhibited VSV transcription. The mono- and diphosphorylated forms of the drug possessed approximately two to three times the inhibitory activity as the triphosphorylated form. Transcripts synthesized in the presence of drug were full length and were absent of incorporated drug. Inhibition by ribavirin 5'-diphosphate could be reversed by the addition of UTP, CTP, and GTP, while the addition of GDP to the reaction did not reverse inhibition. Ribavirin diphosphate was added to a La Crosse virus in vitro transcription assay to determine whether an inhibitory effect could be established in a viral system that was more sensitive to ribavirin than was VSV; it led to profound inhibition of RNA synthesis at concentrations as low as 0.1 microgram/ml. These data suggest that ribavirin has an effect on the initial steps of transcription by some RNA-dependent RNA polymerases and that this effect may be mediated by several phosphorylated forms.
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PMID:Effect of phosphorylated ribavirin on vesicular stomatitis virus transcription. 283 39

F2A8, a glycosylation mutant of Chinese hamster ovary cells, was isolated without prior enrichment or selective procedures by screening colonies for reduced [3H]mannose incorporation into macromolecules. F2A8 cells incubated with [3H]mannose synthesized 70% the amount of labeled GDP-mannose found in parental cells, and the same oligosaccharides attached to lipid and protein as did parental cells, but in reduced amounts. Incorporation of radioactivity from labeled mannose into saccharide-lipids and into total glycopeptides of F2A8 was reduced 7-fold compared to parental cells. In addition, glycosylation of the vesicular stomatitis virus glycoprotein was reduced in F2A8 cells as assessed by a mobility intermediate between normally glycosylated and unglycosylated protein during sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In vitro assays using membrane preparations showed that F2A8 had parental levels of glucosylphosphoryldolichol synthase and of UDP-GlcNAc:dolichyl phosphate:GlcNAc-phosphotransferase when the enzymatic determinations were done in the presence of exogenous dolichyl phosphate. However, 5-fold less glucosylphosphoryldolichol synthase activity was detected in membranes of F2A8 compared to membranes of parental cells in assays relying on endogenous lipid substrate. F2A8 appears to have reduced amounts of dolichyl phosphate available for its glycosylation reactions.
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PMID:A mutant of Chinese hamster ovary cells with a reduction in levels of dolichyl phosphate available for glycosylation. 339 41

A soluble protein fraction containing L, NS, G and M proteins of vesicular stomatitis virus was prepared by treatment of Triton-disrupted virions with 0.8M NaCl. Incubation of the soluble fraction with beta-32P GDP followed by analysis of the proteins by polyacrylamide gel electrophoresis showed specific labeling of the NS protein. The NS-GDP complex was sensitive to phosphatase treatment, suggesting non-covalent binding. No binding of GDP to NS protein was detected when the soluble fraction was pre-heated at 100 degrees C for 1 min. or Mg++ was omitted from the incubation mixture. The binding was inhibited by ATP consistent with competition for a common nucleotide binding site.
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PMID:Specific binding of guanosine 5'-diphosphate with the NS protein of vesicular stomatitis virus. 630 61

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

Interferons induce a number of different proteins which mediate the antiproliferative, antiviral, and immunomodulatory functions of interferons. Interferon-induced Mx proteins, which confer resistance to influenza, vesicular stomatitis, and measles viruses, contain consensus GTPase sequence elements. Insect cell-produced purified murine Mx1 and human MxA proteins were found to hydrolyze GTP with Km = 65 microM (Vmax, 7.1 min-1) and 62 microM (Vmax, 3.1 min-1), respectively. The GTPase activity of Mx1 and MxA proteins was strictly dependent on Mg2+ ions. Murine Mx1 protein was inactivated at 10 degrees C lower temperatures than MxA protein. As analyzed, by filter binding assay, Mx1 protein (at 1 microM) showed a relatively high affinity for GDP (Kd = 1.0 x 10(-7) M) and approximately 340-fold lower affinity for guanosine 5'-3-O-(thio)triphosphate (GTP gamma S) (Kd = 3.4 x 10(-5) M). The Kd values for MxA protein were 2.0 x 10(-7) M for GDP and 5.9 x 10(-6) M for GTP gamma S, showing approximately a 30-fold affinity difference. ATP, UTP, or CTP did not inhibit the Mx protein-dependent GTPase activity, suggesting that Mx1 and MxA proteins are highly specific for guanosine nucleotides. In conclusion recombinant nuclear murine Mx1 and cytoplasmic human MxA proteins show clear differences in their enzymatic activities and nucleotide binding characteristics. How these differences influence their cellular functions and antiviral potential is presently not known.
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PMID:Enzymatic characterization of interferon-induced antiviral GTPases murine Mx1 and human MxA proteins. 750 89

Mx proteins have molecular masses between 70 and 80 kDa and their synthesis is tightly regulated by interferons in mammalian and non-mammalian vertebrates. Some Mx proteins function as intracellular mediators of the interferon-induced antiviral state. When suitable cDNA constructs were constitutively expressed in mouse 3T3 cells the mouse nuclear Mx1 protein conferred selective resistance to influenza virus. The human cytoplasmic MxA protein conferred resistance to influenza virus and vesicular stomatitis virus but not to other viruses. Mx1 blocks influenza virus mRNA synthesis within the nucleus of infected cells. Mx1 presumably interacts with the influenza virus polymerase subunit PB2, because overexpression of PB2 titrates out the Mx1 block. MxA does not inhibit mRNA synthesis of influenza virus; it inhibits a subsequent cytoplasmic viral multiplication step. A possible target is the transport of newly synthesized influenza virus polymerase proteins back to the nucleus. Inhibition by MxA of vesicular stomatitis virus, which replicates in the cytoplasm, is at the transcriptional level. Parts of the N-terminal halves of all known Mx proteins are highly conserved. They contain the typical GTP-binding motif and show significant homology to other members of a new family of GTPases that includes rat dynamin, Drosophila Shibire and the yeast proteins Vps1/Spo15 and Mgm1. Purified Mx1 and MxA proteins possess GTPase activity. The GTP/GDP conversion rates are about 40 per min, and Km values about 700 microM. Mx1 and MxA variants with mutations in the GTP-binding sequences that violate the consensus are unable to confer virus resistance in vivo or to hydrolyse GTP in vitro, suggesting that GTPase activity is necessary for antiviral activity of Mx proteins. We hypothesize that the antivirally active Mx proteins (directly or indirectly) bind to polymerase proteins of susceptible viruses, thereby abolishing normal viral polymerase function. Interaction of Mx with viral targets is probably a GTP-dependent process.
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PMID:Mx proteins: GTPases involved in the interferon-induced antiviral state. 750 12

Two new members (Sar1a and Sar1b) of the SAR1 gene family have been identified in mammalian cells. Using immunoelectron microscopy, Sar1 was found to be restricted to the transitional region where the protein was enriched 20-40-fold in vesicular carriers mediating ER to Golgi traffic. Biochemical analysis revealed that Sar1 was essential for an early step in vesicle budding. A Sar1-specific antibody potently inhibited export of vesicular stomatitis virus glycoprotein (VSV-G) from the ER in vitro. Consistent with the role of guanine nucleotide exchange in Sar1 function, a trans-dominant mutant (Sar1a[T39N]) with a preferential affinity for GDP also strongly inhibited vesicle budding from the ER. In contrast, Sar1 was not found to be required for the transport of VSV-G between sequential Golgi compartments, suggesting that components active in formation of vesicular carriers mediating ER to Golgi traffic may differ, at least in part, from those involved in intra-Golgi transport. The requirement for novel components at different stages of the secretory pathway may reflect the recently recognized differences in protein transport between the Golgi stacks as opposed to the selective sorting and concentration of protein during export from the ER.
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PMID:Sar1 promotes vesicle budding from the endoplasmic reticulum but not Golgi compartments. 813 75

Using three different trans dominant mutants of bovine ARF1 affecting GDP exchange or GTP hydrolysis we demonstrate the central role of ARF1 in controlling vesicular traffic from the endoplasmic reticulum (ER) to the Golgi apparatus and between successive Golgi compartments. Overexpression of ARF1(Q71L), a mutant likely to be restricted to the GTP-bound form, resulted in the accumulation of vesicular stomatitis virus glycoprotein in pre-Golgi intermediates, inhibited transport between successive Golgi compartments, and led to a striking association of beta-COP with pre-Golgi intermediates and the Golgi stack. In contrast, ARF1(T31N), a mutant which is likely to have a preferential affinity for GDP compared to the wild-type protein, inhibited export from the ER and triggered a brefeldin A-like phenotype, resulting in the redistribution of beta-COP from Golgi membranes to the cytosol and the collapse of the Golgi into the ER. This mutant, which may efficiently sequester an ARF-specific guanine nucleotide-exchange protein (ARF-GEF), suggests that ARF and ARF-GEF are essential for export from the ER. These results are discussed in the context of the GDP and GTP-bound forms of ARF in controlling both membrane structure and vesicular traffic through the early secretory pathway.
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PMID:Dominant inhibitory mutants of ARF1 block endoplasmic reticulum to Golgi transport and trigger disassembly of the Golgi apparatus. 828 10


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