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)

Ribonucleoprotein (RNP) cores of influenza virus A/PR/8/34 were dissociated into RNA polymerase (PB1-PB2-PA complex)-associated genome RNA and nuclear protein (NP) fractions by CsCl centrifugation. The RNA polymerase-RNA complexes were capable of catalyzing the endonucleolytic cleavage of capped RNA, the initiation of primer-dependent RNA synthesis, and the synthesis of small-sized RNA, but were unable to synthesize template-sized RNA. By adding the NP protein to the RNA polymerase-RNA complexes, RNP (RNA polymerase-RNA-NP) complexes were reconstituted; they synthesized template-sized transcripts as did native RNP cores. These observations are consistent with the model where viral RNA polymerase is composed of the three P proteins while NP is essential for the elongation of RNA chains. RNP was completely dissociated into RNA-free proteins (PB1, PB2, PA, and NP) and a protein-free genome RNA fraction by centrifugation in cesium trifluoroacetate (CsTFA) and glycerol. By mixing the protein and RNA fractions, primer-dependent RNA-synthesizing activity was regained. These complexes, however, produced only small-sized RNA, presumably due to incorrect assembly of NP on viral RNA.
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PMID:RNA polymerase of influenza virus: role of NP in RNA chain elongation. 324 63

The response of isolated rat liver and murine erythroleukemia nuclei to phospholipid liposomes has been monitored with different techniques, by studying the endogenous RNA synthesis, the release of transcripts in the medium, the pattern of acid-extractable nuclear proteins and the ultra-structural morphology. Total transcription in rat liver and beta-globin mRNA synthesis in MEL nuclei are increased by PS and reduced by PC. These changes of RNA polymerase activity, and the transport of RNAs from nucleus as well as the nuclear protein changes, correlate with structural transitions which occur in both types of nuclei, consisting of euchromatization with loss of RNP particles in the case of PS and opposite effects with PC. The significance of these modifications in relationship to the possible involvement of phospholipids in the control of gene expression is discussed.
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PMID:Effect of phospholipids on transcription and ribonucleoprotein processing in isolated nuclei. 346 78

We have used a microinjection technique to examine whether injected phosvitin, in its capacity as substrate for casein kinase NII, could compete out the endogenous phosphorylation of some nuclear phosphoproteins with regulatory potential and thereby interfere with the activity of RNA polymerase II. Phosphorylation, which utilizes ATP as phosphate donor, was separated from phosphorylation which uses GTP. Phosvitin introduced into nuclei of salivary gland cells becomes phosphorylated by the endogenous nuclear protein kinase(s) and incorporates phosphates from ATP as well as from GTP. The phosphorylation of nuclear proteins and phosvitin is heparin-sensitive, indicating that they are phosphorylated by casein kinase NII. Microinjected phosvitin does not seem to affect the incorporation of phosphate groups from ATP into nuclear proteins, but protein phosphorylation by GTP is influenced. Apart from a minor overall reduction of 32P-incorporation, the phosphorylation of a 42 kDa nuclear protein, a putative transcription stimulatory factor, and of a 115 kDa nuclear protein was competed out by 70%-80% compared with the control value obtained in the absence of phosvitin. Parallel analyses of DNA transcription in phosvitin-injected nuclei showed that the RNA polymerase II-mediated synthesis of hnRNA and Balbiani ring RNA was diminished by 80% and 90%, respectively. In contrast, the transcription of nucleolar pre-ribosomal 38 S RNA by RNA polymerase I remained unaffected. The inhibitory effect of injected phosvitin could be reversed by in vitro phosphorylation of phosvitin prior to injection, using isolated nuclei as source of protein kinase(s). Taken together, the results suggest a causal relationship between the modification of the GTP-dependent phosphorylation of specific non-histone proteins and the activity of RNA polymerase II.
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PMID:Selective repression of RNA polymerase II by microinjected phosvitin. 347 Jan 71

1alpha,25-dihydroxyvitamin D(3) was examined for its ability to affect the DNA-dependent RNA polymerases (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) of rachitic chick intestinal cell nuclei in vivo. Nucleoplasmic (form II) RNA polymerase activity was stimulated 2-fold (P < 0.05) within 2-3 hr after an oral dose of 0.27 mug (0.65 nmol) of 1alpha,25-dihydroxyvitamin D(3) to rachitic chicks. The form II polymerase activity returned to control values by 5-9 hr after dosing with the sterol. In contrast, the nucleolar (form I) RNA polymerase was not increased within this period. Solubilization of nuclear protein and resolution of the two RNA polymerases on DEAE-Sephadex also revealed that there was an increase in polymerase II activity when assayed on exogenous DNA template. This evidence suggests that 1alpha,25-dihydroxyvitamin D(3) acts at the level of the enzymology of intestinal cell transcription and that increased mRNA synthesis after administration of this hormone cannot be due solely to a change in chromatin template activity.
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PMID:Rapid enhancement of chick intestinal DNA-dependent RNA polymerase II activity by 1 alpha, 25-dihydroxyvitamin D3, in vivo. 452 9

A stimulatory factor of DNA-dependent RNA polymerase B (nucleosidetriphosphate: RNA nucleotidyltransferase, EC 2.7.7.6) in nonhistone proteins was partially purified from rat liver nuclei on a column of daunomycin-CH Sepharose 4B and of phosphocellulose. In the process of purification, the stimulatory factor was separated from the main fraction of nuclear protein kinase (ATP: protein phosphotransferase, EC 2.7.1.37). This factor enhanced specifically the activity of RNA polymerase B on rat liver DNA as template and did not affect RNA polymerase A and Escherichia coli RNA polymerase at all. The polynucleotide elongation rate was increased by the addition of this factor.
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PMID:Partial purification of a stimulatory factor of RNA polymerase B in nonhistone proteins; correlation with nuclear protein kinase. 617 81

A large body of circumstantial evidence indicates that receptors located in nuclei of T3 responsive tissues represent a site of initiation of thyroid hormone action at the cellular level. Partial characterization of T3 receptors indicates that these proteins are monomeric structures in nuclei and are chromatin-associated non-histone proteins. Treatment of rat liver nuclei with either pancreatic DNase I or micrococcal nuclease releases T3 receptors from nuclei in two forms: a predominant (95 400 Mr; 5.5-6.0S) and a minor (265 000-365 000 Mr; 12.5S) nucleoprotein complex. Similar structures are excised from rat kidney, brain, and heart nuclei and from GH1 pituitary cell nuclei by micrococcal nuclease digestion. These endonuclease-excised receptor-containing complexes are significantly larger than the salt-extracted receptor (50 000 Mr; 3.5S). The presence of DNA and other non-receptor proteins in these structures indicates that T3 receptors probably function within multimeric complexes in vivo. Although T3 receptors appear to be associated with DNA between nucleosomes, i.e. linker DNA, it is not entirely clear whether all or only a fraction of T3 receptors interact with nucleosomal components. The 12.5S receptor-containing nucleoprotein complex may represent T3 receptors in association with linker DNA and nucleosomal components. T3 receptors do not appear to be uniformly distributed to all chromatin fractions, but are associated with structures having characteristics of transcriptionally active chromatin. They are found in a region of chromatin which is enriched in RNA polymerase activity, rapidly labeled RNA and non-histone proteins, and depleted of histone Hl. This region is also highly sensitive to both micrococcal nuclease and pancreatic DNase I digestion. The association of receptors with transcriptionally active chromatin, however, must be considered provisional until additional details of the precise receptor-chromatin interaction have been established. The recent demonstration of a 20-fold increase in a specific hepatic mRNA four hours following administration of T3 to hypothyroid rats indicates that thyroid hormone potentially has very rapid effects on hepatic gene expression. However, significant changes in nuclear protein phosphorylation, nuclear protein composition, and chromatin structure have not been detected within this four-hour period. Thus, effects of T3 on hepatic gene expression are brought about by local and presumably subtle changes in nuclear function.
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PMID:Association of thyroid hormone receptors with chromatin. 631 18

Nuclear protein kinases include enzymes that transfer the gamma-phosphate of ATP to serine, threonine, lysine or histidine in proteins. Nuclear kinases with a preference for basic proteins are known as histone kinases; those preferring acidic protein substrates are casein kinases. Histone kinases include both cyclic AMP-independent protein kinases and cyclic AMP-dependent protein kinases. The best-characterized cyclic AMP-independent nuclear protein kinase is associated with cell proliferation and is activated (or transported to the nucleus) in G2 phase of the cell cycle. It phosphorylates specific serine and threonine residues in the non globular domains of histone H1 and appears to promote chromosome condensation. The cyclic AMP-dependent protein kinase has unknown nuclear function(s), although it may be translocated from cytoplasm to nucleus in response to specific hormonal stimuli which are also associated with changes in transcriptional activity. There is a massive peak of nuclear cyclic AMP-dependent protein kinase activity in G2 phase of the cell cycle. Nuclear casein kinases are apparently very heterogeneous. Two of these enzymes have been purified to homogeneity. They phosphorylate non-histone chromosomal proteins, including RNA polymerase and ornithine decarboxylase. Phosphorylated ornithine decarboxylase is inactive enzymatically but, in Physarum, it binds to the rDNA minichromosome and stimulates rRNA transcription. Kinases forming phosphoramidate bonds occur in a variety of rat tissues and form phosphohistide in histone H4 and phospholysine in histone H1.
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PMID:Nuclear protein kinases. 632 62

Relative to resting liver, Morris hepatomas with different growth rates (3924A, 5123D, 7800, and 7777) all had higher (two to eightfold) levels (activity/gm tissue) of RNA polymerase I. Only the most rapidly growing tumor (hepatoma 3924A) showed a substantial increase (fivefold) in RNA polymerase III activity. RNA polymerase II activity/gm tissue in the hepatomas was similar to that in resting liver. The elevation in the hepatoma RNA polymerase I activity resulted from both an increase in the number of transcriptionally active enzyme molecules and an increase in the specific activity of the enzyme as a result of phosphorylation. Phosphorylation of RNA polymerase I from Morris hepatoma 3924A could be catalyzed either by an endogenous protein kinase or by a highly purified preparation of NII protein kinase from the same tumor. Three out of eight polypeptides (Mr 120,000, 65,000, and 25,000) or RNA polymerase I were phosphorylated. Phosphorylation resulted in enhanced RNA synthesis at the level of chain elongation. Another nuclear protein kinase, NI, had no significant effect on RNA polymerase I. The activity and/or amount of the NII protein kinase was significantly reduced in resting liver, which correlated with decreased specific activity of the liver RNA polymerase I. Anti-RNA polymerase I antibodies were found in the sera of patients with rheumatic autoimmune diseases such as systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), and rheumatoid arthritis (RA). Sera from these patients were capable of specifically inhibiting RNA polymerase I activity in vitro. Antibodies were produced predominantly against three of the polypeptides--S3 (Mr 65,000), S4 (Mr 42,000), and S5 (Mr 25,000) of RNA polymerase I. The spectrum and proportion of the antibodies against these three subunits differ with each patient and with the type of the autoimmune disease. These observations indicate that (1) the NII kinase can regulate RNA polymerase I activity, (2) protein kinase NII is associated with the polymerase I enzyme complex, and (3) certain polypeptides of this enzyme complex may be the target antigens in rheumatic autoimmune disease.
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PMID:Regulation of RNA polymerase I by phosphorylation and production of anti-RNA polymerase I antibodies in rheumatic autoimmune diseases. 660 44

The distribution of nuclear ribonucleoprotein (hnRNP) particles in Drosophila polytene chromosomes has been investigated using anti-B-36 serum as a probe. The use of polytene chromosomes allows resolution at the level of the chromomere, and provides the opportunity to look for both positive and negative correlations with transcriptional activity. The antiserum was obtained using the nuclear protein B-36 from Physarum polycephalum as the immunogen. It has been shown to precipitate hnRNP particles from HeLa cells through a cross-reaction with the major 32,000- and 34,000-dalton hnRNP particle proteins. The antiserum cross-reacts with a Drosophila nuclear protein of approximately 34,000 daltons. By indirect immunofluorescence, we observed that the antiserum reacts preferentially with transcriptionally active loci of the polytene chromosomes, whereas loci previously or subsequently active do not show significant fluorescence. The overall pattern of fluorescence is very similar to that generated with anti-RNA polymerase B serum. The correlation of fluorescence and transcriptional activity observed suggests that the anti-B-36 serum is recognizing hnRNP proteins which have combined with nascent RNA molecules at the sites of transcription.
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PMID:Distribution studies on polytene chromosomes using antibodies directed against hnRNP. 678 80

Our previous work [Levinger, L. & Varshavsky, A. (1982) Cell 28, 375-385] has shown that D1, a 50-kilodalton chromosomal protein of Drosophila melanogaster, is specifically associated with isolated nucleosomes that contain a complex A + T-rich satellite DNA with buoyant density of 1.688 g/ml. We show here that D1 is also a component of nucleosomes containing a simple-sequence, pure A + T satellite DNA, buoyant density 1.672 g/ml. Furthermore, using a modification of a protein blotting technique in which proteins are not exposed to dodecyl sulfate denaturation, we have found that D1 preferentially binds to A + T-rich double-stranded DNA in vitro, and it is apparently the only abundant nuclear protein in cultured D. melanogaster cells that possesses this property. Synthetic poly[d(A-T)].poly[d(A-T)] and poly(dA).poly(dT) duplexes effectively compete in vitro with A + T-rich D. melanogaster satellite DNAs for binding to D1, whereas total Escherichia coli DNA is an extremely poor competitor. These findings strongly suggest that D1 is a specific component of A + T-rich, tandemly repeated, heterochromatic regions, which constitute up to 15-20% of the total D. melanogaster genome. Possible functions of D1 protein include compaction of A + T-rich heterochromatin and participation in microtubule-centromere interactions in mitosis. In addition, D1 may prevent nonspecific binding to A + T-rich satellite DNA of other nuclear proteins that have a preference for AT-DNA, such as RNA polymerase or regulatory proteins, and may also participate in the higher-order chromatin organization outside tandemly repetitive regions by binding to nonrandomly positioned stretches of A + T-rich DNA.
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PMID:Protein D1 preferentially binds A + T-rich DNA in vitro and is a component of Drosophila melanogaster nucleosomes containing A + T-rich satellite DNA. 681 40


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