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)

We have studied the effect of protein phosphokinase (EC 2.7.1.37; ATP:protein phosphotransferase) and phosphoprotein phosphatase (EC 3.1.3.16; phosphoprotein phosphohydrolase) on reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) activity of Rous sarcoma virus. Protein kinase from Rous sarcoma virus-transformed chick embryo fibroblasts was purified by DEAE-cellulose chromatography, Sephadex gel filtration, and isoelectric focusing. Purified reverse transcriptase from Rouse sarcoma virus was preincubated with protein kinase and ATP under conditions allowing incorporation of phosphate into substrate protein. After the preincubation, reverse transcriptase activity was assayed in the presence of poly(rA).oligo(dT) as template. A 2- to 5-fold increase of reverse transcriptase activity was found after the preincubation of reverse transcriptase with protein kinase and ATP. Incubation of reverse transcriptase with heat-treated, inactive protein kinase and ATP had no effect on transcriptase activity. When the transcriptase preparation was incubated with protein kinase and [gamma-32P]ATP and subsequently purified by chromatography on phosphocellulose and Sephadex gel filtration, significant amounts of 32P-labeled proteins were found in the fractions exhibiting reverse transcriptase activity, suggesting 32P incorporation into transcriptase or transcriptase-associated proteins. A 20-60% decrease of reverse transcriptase activity was observed after incubation of reverse transcriptase with phosphatase. The results suggest that phosphorylative modification of reverse transcriptase may be critical in the regulation of reverse transcriptase-catalyzed DNA synthesis.
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PMID:Protein kinase and its regulatory effect on reverse transcriptase activity of Rous sarcoma virus. 5 72

A substance has been purified from isolated nuclei of Physarum polycephalum by equilibrium and velocity gradient centrifugations, ion exchange chromatography and gel filtration which has a high molecular weight, can be labeled in vivo with 32P, is heat stable and resistant to amylases, proteases, nucleases and phosphodiesterase but is sensitive to phosphatases or hydrolysis. This material consists of phosphate and glycerol. It selectively inhibits in vitro transcription of RNA polymerases, predominantly the homologous enzyme A by binding to the enzyme. In the presence of this inhibitor of transcription a stable RNA polymerase-template complex cannot be formed. Binding to and inactivation of RNA polymerase is reversible at high ionic strength.
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PMID:Characterization of an endogenous transcription inhibitor from Physarum polycephalum. 15 53

Non-histone chromosomal proteins are phosphorylated and dephosphorylated within the intact nucleus by two independent sets of reactions, a protein kinase reaction which transfers the terminal phosphate group of a variety of nucleoside and deoxynucleoside triphosphates to serine and threonine residues in the proteins, and a phosphatase reaction which cleaves these phosphoserine and phosphothreonine bonds and releases inorganic phosphate. Several lines of evidence are consistent with the hypothesis that the phosphorylation and dephosphorylation of these proteins is involved in gene control mechanisms, including the findings that phosphorylated non-histone proteins are highly heterogeneous and their phosphorylation patterns are tissue specific, changes in their phosphorylation correlate with changes in chromatin structure and gene acticity, addition of phosphorylated non-histone proteins increases RNA synthesis in vitro. and phosphorylated non-histone proteins bind specifically to DNA. Cyclic AMP has both stimulatory and inhibitory properties on non-histone protein phosphorylation, depending on the enzyme fraction and substrate employed A specific protein component whose phosphorylation is inhibited by cyclic AMP has been found to be associated with RNA polymerase. The cyclic AMP-induced decrease in the phosphorylation of this protein correlates with an enhancement of RNA synthesis in vitro. These results suggest that both phosphorylation and dephosphorylation of chromatin-associated proteins may be involved in the control of gene readout.
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PMID:Phosphorylation of non-histone proteins in the regulation of chromosome structure and function. 16 80

The 5' terminal structure of the mRNA synthesized in vitro by the virion-associated RNA polymerase of vesicular stomatitis virus in the presence of S-adenosyl-L-methione consists of 7-methyl guanosine linked to 2'-O-methyl adenosine through a 5'-5' pyrophosphate bond as m7G(5')ppp(5')A-m-p ... The alpha and beta phosphated of GTP and alpha phosphate of ATP are incorporated into the blocked 5' terminal structure.
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PMID:The 5' terminal structure of the methylated mRNA synthesized in vitro by vesicular stomatitis virus. 16

Cultures of the rat skeletal muscle myoblast cell line, L6, were treated with the mutagen ethylmethanesulfonate and grown in the presence of alpha-amanitin, an inhibitor of RNA polymerase II in vitro. One clonal cell line, Ama102, resistant tc the cytotoxic action of 2 mu-g/ml of alpha-amanitin was isolated and extensively characterized. Ama102 cells were about 30-fold more resistant to alpha-amanitin than their Ama+ parent cells based on a comparison of the concentration of alpha-amanitin required to reduce their plating efficiencies to similar extents. The RNA polymerase activities from Ama+ and Ama102 cells were solubilized and separated by DEAE-Sephadex chromatography. Whereas all of the Ama+ RNA polymerase II activity was inhibited by 0.1 mu-g/ml of alpha-amanitin, about 30% of the activity in the Ama102 RNA polymerase II peak was resistant to this concentration of alpha-amanitin and was inhibited only by much higher concentrations (25 mu-g/ml) of alpha-amanitin. This alpha-amanitin-resistant activity in Ama102 cells was identified as a bona fide RNA polymerase II by its chromatographic behavior on DEAE-Sephadex, salt optimum, preference for denatured DNA as template, insensitivity to inhibition by potassium phosphate, thermal inactivation kinetics, and inactivation by anti-RNA polymerase II antiserum. Both RNA polymerase IIa and IIb from Ama102 cells exhibited the partial alpha-amanitin resistance, as did this activity when purified further on phosphocellusose. Unlike the parental Ama+ cells, Ama102 cells neither fused at confluence nor showed an increase in the specific activity of creatine kinase. The altered sensitivity of the Ama102 RNA polymerase II to alpha-amanitin appears to account for the drug-resistant phenotype of these cells.
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PMID:Isolation and characterization of an alpha-amanitin-resistant rat myoblast mutant cell line possessing alpha-amanitin-resistant RNA polymerase II. 16 92

Nucleoplasmic RNA polymerase II (nucleosidetriphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) from calfthymus is phosphorylated by homologous cyclic AMP-independent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37). Polyacrylamide gel electrophoresis of the 32P-labeled RNA polymerase II under non-denaturing conditions revealed that both forms of the enzyme were phosphorylated. Polyacrylamide gel electrophoresis of the 32P-labeled RNA polymerase II under denaturing conditions showed that the 25 000 dalton subunit was the phosphate acceptor subunit. Partial acid hydrolysis of the 32P-labeled RNA polymerase II followed by ion-exchange chromatography revealed serine and threonine as the [32P]phosphate acceptor amino acids. Phosphorylation of the RNA polymerase II was accompanied by a stimulation of enzymatic activity and was dependent upon the presence of ATP.
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PMID:Phosphorylation of calf thymus RNA polymerase II by nuclear cyclic 3',5'-AMP-independent protein kinase. 20 18

The mechanism of the priming effect of luteinizing hormone releasing factor (LH-RF) upon gonadotrophin secretion was studied using short-term incubation of hemipituitary glands from pro-oestrous rats. The dependence of the priming, but not the LH releasing action of LH-RF on protein synthesis in pituitary tissue was confirmed. Cytochalasin B failed to affect the first response to LH-RF, but abolished the priming effect, suggesting that the integrity of cellular microfilaments was essential. Colchicine and vinblastine did not modify the response to LH-RF. Neither inhibitors of DNA nor the inhibitor of RNA polymerase II, alpha-amanitin, significantly affected the priming action of LH-RF. Normal extracellular concentrations of Ca2+ were necessary for gonadotrophin release, but the priming effect was not significantly affected by low extracellular Ca2+ and could not be elicited by raising intracellular Ca2+ concentrations. Adenosine 3':5'-cyclic phosphate did not appear to act as a second messenger for either the gonadotrophin releasing or the priming action of LH-RF.
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PMID:Priming effect of luteinizing hormone releasing factor in vitro: role of protein synthesis, contractile elements, Ca2+ and cyclic AMP. 22 30

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

Because influenza viral RNA transcription in vitro is greatly enhanced by the addition of a primer dinucleotide, ApG or GpG, we have proposed that viral RNA transcription in vivo requires initiation by primer RNAs synthesized by the host cell, specifically by RNA polymerase II, thereby explaining the alpha-amanitin sensitivity of viral RNA transcription in vivo. Here, we identify such primer RNAs, initially in reticulocyte extracts, where they are shown to be globin mRNAs. Purified globin mRNAs very effectively stimulated viral RNA transcription in vitro, and the resulting transcripts directed the synthesis of all the nonglycosylated virus-specific proteins in micrococcal nuclease-treated L cell extracts. The viral RNA transcripts synthesized in vitro primed by ApG also directed the synthesis of the nonglycosylated virus-specific proteins, but the globin mRNA-primed transcripts were translated about 3 times more efficiently. The translation of the globin mRNA-primed, but not the ApG-primed, viral RNA transcripts was inhibited by 7-methylguanosine 5'-phosphate in the presence of S-adenosylhomocysteine, suggesting that the globin mRNA-primed transcripts contained a 5'-terminal methylated cap structure. We propose that this cap was transferred from the globin mRNA primer to the newly synthesized viral RNA transcripts, because no detectable de novo synthesis of a methylated cap occurred during globin mRNA-primed viral RNA transcription. Preliminary experiments indicate that other purified eukaryotic mRNAs also stimulate influenza viral RNA transcription in vitro.
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PMID:Globin mRNAs are primers for the transcription of influenza viral RNA in vitro. 28 99

An acidic nucleolar phosphoprotein with a subunit M(r) of 70,000 was purified as an apparent dimer of 139,000 from isolated nuclei of the slime mold Physarum polycephalum. The protein was purified without the aid of strong dissociating agents after its selective phosphorylation in isolated nuclei by a polyamine-mediated reaction. Its amino acid composition resembled that of a nucleolar phosphoprotein from Novikoff hepatoma ascites cells. The phosphoprotein stimulated rRNA synthesis 5-fold by RNA polymerase I within a nucleolar, ribosomal deoxyribonucleoprotein complex isolated from nucleoli of P. polycephalum. It was also identified as a component of the complex. It bound with high affinity and specificity to the palindromic ribosomal DNA of 38 x 10(6)M(r) from P. polycephalum, which contained two coding sequences for 5.8S, 19S, and 26S rRNA. It also bound to three fragments of ribosomal DNA of M(r) 21.2 x 10(6), 17.1 x 10(6), and 8.1 x 10(6), prepared by cleavage with restriction endonucleases HindIII, PstI, and BamHI, respectively. All of these fragments included the symmetry axis of the palindromic ribosomal DNA. The phosphoprotein that had been treated with alkaline phosphataseagarose to hydrolyze the phosphate groups did not stimulate transcription and did not bind to ribosomal DNA or to the restriction fragments indicated. We have thus isolated a specific phosphoprotein with the capacity to stimulate transcription of a specific set of genes in a eukaryote. These findings suggest that this phosphoprotein may specifically regulate functions of ribosomal DNA in a manner dependent on its degree of phosphorylation.
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PMID:Polyamine-mediated phosphorylation of a nucleolar protein from Physarum polycephalum that stimulates rRNA synthesis. 28 43


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