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)

RNA polymerase 1 activity and nucleolar volume have been reported to increase in hepatocytes from rats fed a protein-free diet. Phosphorylation in vitro of a 110-kDa protein was enhanced in nuclei and nucleoli from livers of rats fed a protein-free diet. In nuclear extracts the 110-kDa protein in heat-treated nuclei was much more phosphorylated than from control liver. In contrast, casein kinase activity in the nuclear extract from control liver was comparable to that from livers of rats fed a protein-free diet. Nuclear extracts from control rat liver and livers of rats fed a protein-free diet were fractionated by DEAE-cellulose column chromatography. Casein kinase II (NII) eluted at around 0.17 M NaCl scarcely phosphorylates the 110-kDa protein. Chromatography of the nuclear extract from livers of rats fed a protein-free diet, but not from control liver, yielded fractions which eluted at 0.21-0.25 M NaCl and predominantly phosphorylated the 110-kDa protein. The phosphorylation of 110-kDa protein was not appreciably affected by a heparin concentration of 5 micrograms/ml, which completely inhibited casein kinase II. In addition, phosphorylation of the 110-kDa protein in liver nucleoli from rats fed a protein-free diet showed a lower sensitivity to heparin than that in control rat liver nucleoli. These results suggest that enhanced phosphorylation of the nuclear 110-kDa protein in livers from rats fed a protein-free diet is due to the induction of a 110-kDa protein kinase distinct from casein kinase II.
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PMID:Enhanced phosphorylation of a nucleolar 110-kDa protein in rat liver by dietary manipulation. 216 18

Various agents were tested for their effects on microbial proteases, which activity was monitored by the analysis of cleaved peptide bands in SDS-polyacrylamide gel electrophoresis. Using casein as a substrate, fungal protease (type XIX) was inhibited by the phenyl methyl sulphonyl fluoride, chymostatin, antipain and leupeptin, while bacterial protease (type XXVI) was inhibited by phosphatidyl glycerol, phosphatidyl inositol and sphingosine. MS2 RNA exerted minor inhibition on the bacterial proteolysis of regulatory subunits of cyclic AMP-dependent protein kinase (A-PK). The cleavage of DNA binding protein by both proteases was inhibited, in the presence of MS2 RNA and lambda DNA. In comparison, phosphatidyl serine slightly stimulated the fungal protease on the cleavage of ribonuclease T1. RNA polymerase is a good substrate of the bacterial protease as indicated by the generation of multiple cleaved peptide fragments, whereas alkaline phosphatase is not susceptible to proteolysis.
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PMID:A further study on the regulation of microbial proteases. 222 36

To investigate myeloid cell maturation, we established a panel of monoclonal antibodies that recognize myeloid cell nuclear antigens. One of these monoclonal antibodies was used to purify a specific protein complex (PC) from a human spleen. This PC, which is present at high levels in peripheral blood monocytes and granulocytes, contains a protein that is the cystic fibrosis (CF) antigen. The purified PC was shown to inhibit the activity of casein kinase I and II but not cAMP-dependent protein kinase, protein kinase C, v-abl tyrosine kinase, or insulin receptor tyrosine kinase. The observed Ki values for casein kinases I and II purified from several sources were 1 microM or less. Furthermore, the addition of the purified PC to a nuclear extract from human cells was able to prevent protein kinase-mediated stimulation of RNA polymerase activity. The unique inhibitory character of the PC and its elevated levels in monocytes and granulocytes and of the CF antigen in CF patients implies that this complex may be associated with myeloid cell functions and perhaps with the cause or consequence of the clinical manifestations of CF.
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PMID:A protein containing the cystic fibrosis antigen is an inhibitor of protein kinases. 265 77

The adenosine analogue 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) is a specific inhibitor for RNA polymerase II transcription in vivo and in vitro [Tamm + Sehgal (1978) Adv. Virus Res. 22, 187-258; Zandomeni & Weinmann (1984) J. Biol. Chem. 259, 14804-14811]. The effect on RNA polymerase II-specific transcription seems to be mediated by its inhibition of nuclear casein kinase II [Zandomeni, Carrera-Zandomeni, Shugar & Weinmann (1986) J. Biol. Chem. 261, 3414-3419]. Inhibition studies indicated that DRB acted as a mixed-type inhibitor with respect to casein and as a competitive inhibitor with respect to the nucleotide phosphate donor substrates. The DRB inhibition constant is 7 microM for the calf thymus casein kinase II, with regard to both ATP and GTP.
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PMID:Kinetics of inhibition by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole on calf thymus casein kinase II. 280 63

The activities of the three DNA-dependent RNA polymerases from a rapidly growing rat tumour, Morris hepatoma 3924A, and from rat liver were examined. The activity of RNA polymerase I was higher in the tumour than in the liver. The enhanced capacity for RNA synthesis was a result of a higher concentration of polymerase I in the tumour as well as of an activation of this enzyme in vivo. The possibility that the high specific activity of the hepatoma polymerase I resulted from phosphorylation was investigated. Two major cyclic-AMP-independent nuclear casein kinases (NI and NII) were identified; the activity of protein kinase NII in the tumour was ten times that in liver. Protein kinase NII was capable of activating and phosphorylating RNA polymerase I in vitro. This kinase could also stimulate RNA polymerase II activity, although to a lesser extent than RNA polymerase I. RNA polymerase III was not affected by protein kinase NII. Protein kinase NII was tightly associated with polymerase I and was found even in purified preparations of the polymerase. Antibodies against both RNA polymerase I and protein kinase NII were present in sera of patients with certain rheumatic autoimmune diseases. These results imply that RNA polymerase I and protein kinase NII are in close association in vivo as well as in vitro and that polymerase phosphorylation may regulate the rate of ribosomal RNA synthesis in the cell.
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PMID:Phosphorylation of RNA polymerases: specific association of protein kinase NII with RNA polymerase I. 613 1

Protein restriction has been shown to produce either an enhancement or a reduction of transcription activity in vitro. Conditions for an enhanced transcription activity were investigated. Young male rats were fed a complete diet containing either 20% or 3% casein for 6 days. Body weight changed +7.4 g/day and -0.5 g/day, respectively. Liver wet weights were 6.8 and 3.7 g and the DNA amounts/g were 1.31 and 1.67 mg. Liver nuclei were incubated without or with 1 unit micrococcus nuclease (EC 3.1.4.7) per milligram of nuclear DNA, and chromatin was fractionated into a 2,000 x g, a 102,000 x g pellet and a supernatant fraction. In the livers of rats fed a low protein diet, chromatin-bound RNA polymerase I plus III and II activity/mg of fractional and nuclear DNA and soluble RNA polymerase activity were increased, while heparin-stimulated RNA polymerase II activity remained unchanged. An increased number of chains was synthesized by RNA polymerase I plus III without change in chain length and incorporation rate per chain. The length and incorporation rate per chain increased, while the number of chains synthesized by RNA polymerase II did not. After stimulation by heparin, an increased number of short chains was synthesized at a lower rate of incorporation per chain. In the complex chromating structures the capacity for RNA synthesis was determined by specific enzyme activity, RNA chain number and length.
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PMID:Increased transcription activity of rat liver chromatin after protein restriction and limited digestion of nuclei with micrococcus nuclease. 616 33

Restriction of protein intake in the diet has been shown to produce a change in transcription activity as determined in vitro. Conditions for a reduced transcription activity were investigated with selective digestion of nuclei with micrococcus nuclease (EC 3.1.4.7). Liver nuclei from young male rats fed a diet containing either 20 or 3% casein for 6 days were digested with 1.3 microgram of micrococcus nuclease protein/mg of nuclear DNA (specific enzyme activity 15,000 or 150 units/mg of protein). Part of the chromatin-bound RNA polymerase activity was transferred from the 2,000 x g to the 102,000 x g pellet. Independent of the type of endonuclease use, the specific activity of chromatin-bound and soluble RNA polymerase I plus III was similar in the two groups of rats. After protein restriction RNA polymerase II activity was significantly diminished in the 2,000 x g pellet, and was unchanged in the 102,000 x g pellet. Heparin-stimulated and soluble RNA polymerase II activities were significantly reduced. Number and length of RNA chains synthetized by chromatin-bound RNA polymerase I plus III remained unchanged by dietary treatment. After a low protein diet, RNA polymerase II in the absence and presence of heparin synthesized an unchanged number of RNA chains with reduced length. A selective digestion of chromatin with micrococcus nuclease is needed to show the reduction in RNA polymerase II activity after protein restriction.
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PMID:Reduced transcription activity of rat liver chromatin after protein restriction and selective digestion of nuclei with micrococcus nuclease. 616 34

Ornithine decarboxylase (ODC) and nucleolar DNA-dependent RNA polymerase (RNA polymerase I) activities increased in the liver of young adult male rats fed a 6% casein diet (malnourished) for 1 week when compared with rats fed a 25% casein diet (control). ODC activity increased progressively and reached a peak after 3 weeks of malnutrition and then decreased to control values by 5 weeks. RNA polymerase I reached peak activity 1 week after malnutrition was imposed, decreasing thereafter to control values by 3 weeks. At 4 and 5 weeks, RNA polymerase I activity in malnourished animals was lower than control. Nucleoplasmic DNA-dependent RNA polymerase activity remained unchanged in the first 2 weeks of malnutrition and decreased thereafter to values significantly lower than control. The data confirm our previous observations of cyclical changes during prolonged malnutrition and suggests a process of "biochemical adaptation" to malnutrition in which the organism enhances essential metabolic processes to maintain cellular homeostasis to the detriment of less essential functions like systemic growth.
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PMID:Ribonucleic acid metabolism in rat liver during long-term adaptation to malnutrition. 617

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

The adenosine analog 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) inhibits specific in vitro transcription initiation by RNA polymerase II. We report here that DRB inhibits a protein kinase present in an extract of HeLa cells and does not inhibit other protein kinases contained in the same extract. The protein kinase affected by DRB is cyclic AMP independent, prefers acidic protein substrates such as casein and phosvitin, and utilizes GTP as the phosphate donor almost as effectively as ATP in the phosphotransferase reaction. The DRB-sensitive protein kinase is also stimulated by polyamines and inhibited by quercitin and heparin. The biochemical and chromatographic properties of this enzyme correspond to those characteristic of casein kinase II. In HeLa cells, DRB is able to inhibit in vivo phosphorylation on some nuclear proteins. In HeLa cell extracts, in vitro phosphorylation of several proteins by [gamma-32P]GTP is inhibited by DRB. This protein kinase has a DRB sensitivity profile identical to the one previously reported for specific in vitro transcription by RNA polymerase II in a whole-cell extract (Zandomeni, R., Mittleman, B., Bunick, D., Ackerman, S., and Weinmann, R. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 3167-3170). Thus we suggest that this protein kinase mediates DRB inhibition of specific RNA polymerase II transcription in vivo and in vitro.
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PMID:Inhibitory effect of 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole on a protein kinase. 650 18


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