Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The response of mouse L cells to infection with wild-type (wt) and temperature-sensitive (ts) mutants of vesicular stomatitis virus was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to delineate the synthesis of host cell and viral proteins. Experiments utilized transcriptase mutants of complementation group I (ts114 and ts13), a group IV mutant (ts44) that is restricted in total RNA synthesis (RNA-1) but not in primary transcription, and a group II mutant (ts52) variably restricted in RNA synthesis (RNA +/-). L cells infected with ts mutants at permissive temperature exhibited the wt response of progressive inhibition of host cell protein synthesis accompanied by accumulation of all five viral proteins. Mutant ts44 (IV) also switched off cell protein synthesis at restrictive temperature and accumulated all five viral proteins, but with disproportionate ratios of N and G proteins. At restrictive temperature, cells infected with group I ts mutants failed to accumulate any viral protein and did not exhibit significant reduction in host cell protein synthesis. These data suggest that vesicular stomatitis virus inhibits cell protein synthesis at a stage of viral infection after transcription and possibly translation but preceding replication of progeny viral RNA.
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PMID:Differential inhibition of host protein synthesis in L cells infected with RNA - temperature-sensitive mutants of vesicular stomatitis virus. 17 96

The RNA-dependent RNA polymerase associated with vesicular stomatitis virus was isolated to apparent homogeneity by a newly developed procedure, which includes stepwise removal of proteins from virions by successive treatment with high concentrations of cesium sulfate and cesium chloride, followed by glycerol gradient centrifugation or chromatography on phosphocellulose or DEAE-Sephadex column. The polymerase thus purified contained L (large protein) and NS proteins as the intrinsic subunits and multiple species of enzyme were found which differ in the molar ratio of L to NS. Since the enzyme with the highest activity was composed of equimolar amounts of the two subunits and exhibited the sedimentation coefficient of approximately 11 S in a buffer containing 0.2 M NaCl, the structure of active protomer was suggested to be (L)1(NS)1. In accordance with this conclusion, enzyme preparations deficient in the content of NS protein, were activated by the addition of preparations deficient in the content of NS protein. The purified RNA polymerase catalyzed the synthesis of poly(A), which was covalently attached to the 3' termini of RNA products, and RNA, only in the presence of all 4 substrates. The present finding might be the first which indicates that the transcriptase itself catalyzes post-transcriptional modification of mRNA by adding poly(A) sequences to the 3'-OH termini. The molecular mechanism of the switch from transcription to poly(A) synthesis, however, remains to be investigated.
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PMID:Function and structure of RNA polymerase from vesicular stomatitis virus. 18 23

Phosphorylation of rat liver RNA polymerase I occurred when intact rat liver nuclei were incubated with [gamma32P]ATP and N6,O2' dibutyryl cyclic 3':5'-AMP. In addition, partially purified RNA polymerase I could be phosphorylated in vitro by an endogenous protein kinase. Phosphorylation by either method was followed by extensive purification of the enzyme. This revealed that 32P remained bound to the enzyme throughout purification. Analysis of the homogeneous labeled protein by polyacrylamide gel electrophoresis under nondenaturing conditions followed by autoradiography revealed that only one of the two forms of RNA polymerase I in rat liver nuclei was phosphorylated. RNA polymerase II was not phosphorylated in intact nuclei. Polyacrylamide gel electrophoresis of the phosphorylated RNA polymerase I in the presence of 0.1% sodium dodecyl sulfate followed by autoradiography demonstrated that the 32P was located primarily on enzyme subunits SA1, SA3, and SA5-SA6. High voltage paper electrophoresis of a partial acid hydrolysate of phosphorylated RNA polymerase I revealed that both serine and threonine residues were phosphroylated. N6,O2'-Dibutyryl cyclic 3':5'-AMP stimulated endogenous RNA polymerase I activity and endogenous nuclear protein phosphorylation in intact nuclei. These results suggest that phosphorylation of RNA polymerase I by nuclear protein kinases may play a role in the control of transcription in mammalian cells.
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PMID:Phosphorylation of rat liver ribonucleic acid polymerase I by nuclear protein kinases. 18 96

A protein kinase, designed KII, has been purified 5000-fold from Novikoff ascites tumor cells. The purification procedure also allows for the purification of a second major protein kinase, designated KI, as well as RNA polymerase I and II. Purified KII has a sedimentation constant of 7.6 S and a Stokes radius of 39 A, suggesting a molecular weight of about 122000. Polyacrylamide gel electrophoresis of the enzyme in the presence of sodium dodecyl sulfate suggests the enzyme is composed of subunits of molecular weights 44 000, 40 000, and 26 000 present in a molar ratio of 1:1:2. Incubation of the enzyme alone in the presence of [gamma-32P]ATP results in the phosphorylation of the 26 000-dalton subunit. Protein kinase II actively phosphorylates phosvitin, casein, and nonhistone chromosomal proteins but does not phosphorylate basic proteins such as histones or protamine to an appreciable extent. Km values of 3.6 micron for ATP and 6.5 micronM for GTP were determined in the presence of 4mM Mg2+. The enzyme is neither stimulated by cyclic adenosine 3',5'-monophosphate or cyclic guanosine 3', 5'-monophosphate nor inhibited by the regulatory subunit of rabbit muscle protein kinase. Its activity is stimulated by KCl at concentrations below 0.2 M and inhibited by higher concentrations.
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PMID:Purification and characterization of Novikoff ascites tumor protein kinase. 19 79

The nonhistone chromatin protein, C-14, was extracted from chromatin of Novikoff hepatoma ascites cells and isolated in high purity as shown by its migration as a single dense spot on two-dimensional polyacrylamide gels. Its mobility on sodium dodecyl sulfate gels is consistent with a molecular weight of approximately 70 000. The amino acid composition shows that protein C-14 has an acidic:basic amino acid ratio of 1.8. Its amino terminal amino acid is lysine. Protein C-14 stimulated the incorporation of [3H]UMP into RNA by approximately 30% when added to naked DNA and homologous RNA polymerase I. A 30% stimulation of [3H]UMP incorporation into RNA was also found when protein C-14 was added to an E. coli RNA polymerase system containing either E. coli or Novikoff hepatoma DNA.
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PMID:Isolation and characterization of nonhistone chromosomal protein C-14 which stimulates RNA synthesis. 19 58

We have previously described the isolation, from nuclei of monkey cells infected with Simian virus 40 (SV40), of a nucleoprotein complex which is able to achieve viral transcription. This complex contains SV40 DNA and RNA polymerase II molecules which have initiated transcription during the viral development. We show here, by molecular hybridization experiments, that most of the templates active in SV40 transcription can be dissociated from host DNA. In conditions where supercoiled SV40 DNA form I sediments at 21 S, the transcription complex has a sedimentation coefficient of about 25 S. Inhibition of viral DNA synthesis by cytosine arabinonucleoside or chloroquine does not affect the activity of the transcription complex, which suggests that replicating molecules are not required for viral RNA synthesis and that SV40 DNA form I could serve as template for late SV40 transcription. A large fraction of the RNA synthesized in vitro remains associated with the SV40 DNA template in cesium sulfate density gradient. The RNA chains produced by the complex are heterogeneous in size, most of them being as large or larger than the viral genome.
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PMID:Characterization of a soluble simian-virus-40 transcription complex. 19 51

Cellular RNA synthesis was studied in mouse L-929 cells and in these cells infected with mengovirus. RNA polymerases I, II, and III were partially purified and their chromatographic properties were analyzed by DEAE-Sephadex A-25 chromatography. RNA polymerase II was purified from mouse liver and its subunit structure was compared to that of normal and virus-infected L-929 cells by two-dimensional gel electrophoresis. By these criteria, the enzymes from all three sources were identical. The RNA synthetic activities and capacities of chromatins from normal and virus-infected cells were compared under a variety of conditions. The endogenous activity in chromatin from infected cells was inhibited relative to controls but the residual activity responded normally to stimulation by ammonium sulfate, heparin, and Sarkosyl. The template capacity of the chromatins was compared with added RNA polymerase II and by a rifampicin challenge assay utilizing Escherichia coli RNA polymerase. Identical results were obtained in each case. The number of growing RNA chains and the rates of their elongations were determined. The results showed that nuclei and chromatin from infected cells have a smaller number of RNA polymerase II molecules engaged in RNA synthesis than normal cells do but that the active molecules elongate RNA chains at the same rate.
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PMID:Cellular RNA synthesis in normal and mengovirus-infected L-929 cells. 20 39

Polyoma virus complementary RNA, synthesized in vitro by using highly purified Escherichia coli RNA polymerase and nondefective form I polyoma DNA, was translated in a wheat germ cell-free system. Polypeptides were synthesized that comigrated on sodium dodecyl sulfate-polyacrylamide gels with the polyoma capsid proteins VP1 and VP2, although most of the cell-free products were of smaller molecular weights. The VP1-size protein specifically immunoprecipitated with anti-polyoma virus serum, and upon digestion by trypsin yielded [35S]methionine-labeled tryptic peptides that co-chromatographed with the [3H]methionine-labeled tryptic peptides of virion-derived VP1 on both cation-exchange and anion-exchange resins. The VP2-size in vitro product contained all the virion VP2 methionine-labeled tryptic peptides, as shown by cation- and anion-exchange chromatography and two-dimensional fingerprinting on cellulose. We conclude that full-length polyoma VP1 and VP2 are synthesized in response to complementary RNA and consequently that the viral capsid proteins VP1, VP2, and VP3 are entirely virus coded.
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PMID:Polyoma virus complementary RNA directs the in vitro synthesis of capsid proteins VP1 and VP2. 20 20

A method of steady-state electrophoresis in polyacrylamide gels was used to analyze the presence of cyclic nucleotide binding components in cell extracts. Multiple cyclic AMP and cyclic GMP binding components were detected in soluble cytoplasmic and nuclear extracts derived from avian liver, but only a single cyclic GMP binding protein was found in the 0.3 M NaCl extract of liver nucleoli. In the presence of cyclic GMP, this protein phosphorylated efficiently a calf thymus histone mixture and an endogenous nucleolar protein, which migrated identically with histone H4 in sodium dodecyl sulfate polyacrylamide gel electrophoresis. The isoelectric point of the cyclic GMP-binding protein was 4.8. Addition of cyclic GMP did not influence the activity of the endogenous nucleolar RNA polymerase.
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PMID:A cyclic GMP-dependent histone kinase bound to liver nucleoli. 23 90

A procedure for the simultaneous purification of RNA polymerases I, II, and III from Saccharomyces cerevisiae is described. High yields of each enzyme activity are obtained, allowing the preparation of approximately 10 mg of polymerase I, 25 mg of polymerase II, and 12 mg of polymerase III from 1.2 kg of cells (wet weight). Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate indicates RNA polymerase I contains polypeptides with molecular weights 185 000, 137 000, 41 000, 35 000, 28 000, 24 000, 20 000, 16 000, 14 500, and 12 300; RNA polymerase II contains subunits with molecular weights 170 000, 145 000, 41 000, 33 500, 28 000, 24 000, 18 000, 14 500, and 12 500; and RNA polymerase III contains polypeptides with molecular weights 160 000, 128 000, 82 000, 53 000, 41 000, 37 000, 34 000, 28 000, 24 000, 20 000, 14 500, and 10 700.
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PMID:Isolation of ribonucleic acid polymerases I, II, and III from Saccharomyces cerevisiae. 31 51


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