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)

Studies on the effects of substrates on RNA polymerase I [EC 2.7.7.6] in vitro showed that nucleolar RNA synthesis was inhibited by an excess of substrate nucleoside triphosphates in the presence of Mg2+. GTP and UTP were more inhibitory than CTP and ATP. These compounds specfically inhibited nucleolar RNA synthesis and a concentration of GTP that strongly inhibited nucleolar RNA synthesis did not inhibit RNA synthesis by partially purified RNA polymerase I. The inhibition of nucleolar RNA synthesis disappeared at pH 9.0 without any change in the apparent Km for GTP or the Vmax of RNA synthesis.
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PMID:Inhibitory effects of nucleoside triphosphates on nucleolar RNA synthesis. 3 1

Treatment of Streptococcus sanguis recipient cells with rifampin (RIF) at the time of deoxyribonucleic acid (DNA) addition was an effective means of reducing discrimination, that is, of causing an increase in the number of transformants induced by irreversibly bound heterospecific DNA without significantly changing the number induced by bound homospecific DNA. RIF was unable to reduce discrimination when the recipient cells were RIF resistant due to an altered ribonucleic acid (RNA) polymerase. When recipient cells were treated at the time of DNA addition with concentrations of streptolydigin (STG) as inhibitory of RNA synthesis as RIF, discrimination was not reduced. The kinetics of RNA synthesis inhibition with these inhibitors indicated that, as reported for other bacterial species, RIF inhibited the initiation of transcription by RNA polymerase, whereas STG inhibited the progression of RNA polymerase at any point. Pulse-labeling of RNA immediately before STG addition showed that, if cells were incubated under STG inhibition for 10 to 15 min, their nascent RNA was degraded. Genome-bound RNA polymerase was not released under these conditions. When recipient cells were incubated with STG until nascent RNA was degraded and then exposed to transforming DNA, STG was as effective as RIF in reducing discrimination. The presence of nascent RNA was thereby implicated in the transforming inefficiency of incompletely homologous DNA.
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PMID:Enhanced transformability with heterospecific deoxyribonucleic acid upon removal of nascent ribonucleic acid from the Streptococcus sanguis genome. 3 32

RNA polymerase was extracted from the Schmidt-Ruppin strain of Rous sarcoma virus (SR-RSV)-induced C3H/He mouse ascites sarcoma cells (SR-C3H). RNA polymerase was separated into RNA polymerases I and II by DEAE-Sephadex chromatography. RNA polymerase I was separated into Ia and Ib fractions by phospho-cellulose chromatography. In SR-C3H cells RNA polymerase Ib was the main component of RNA polymerase I. At 0.05--0.1 M ammonium sulphate RNA polymerase I transcribed native DNA most actively, and RNA polymerase II transcribed denatured DNA most actively. Partial digestion of DNA by DNAase I enhanced RNA synthesis by RNA polymerases I and II. At ionic strength over 0.2 M ammonium sulphate, the initiation reaction of RNA polymerases I and II was inhibited. The initiation complexes of RNA polymerases I and II with native DNA were more stable against high salt concentration than with denatured DNA.
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PMID:Characterization of RNA polymerases from Rous sarcoma virus-induced mouse ascites sarcoma cells. 3 35

For the elucidation of the age-dependent reduction of the avidin induction in the ovidict of quails, studies on the level of the post-transcriptional events were performed. In estrogen-treated young animals, the extractable activity of DNA dependent RNA polymerase II increases by 145% after progesterone treatment, while in old animals no increase is observed. In the presence of actinomycin D the incorporation ratio [3H] Ado/[3H] Urd into mRNA increases by about 80% in the case of mature animals; this value is drastically lower (15%) using old animals. The activities of the poly(A)-degrading enzymes in oviducts of mature animals are lower than those in old ones. After progesterone treatment the activities of these enzymes increase in oviducts from old animals, while in young quails no alteration is observed. The possible consequence of these findings on the chain length of the poly(A) segment of mRNA is discussed with regard to its translation capacity.
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PMID:[Age-dependent avidin induction. V. Changes on the level of post-transcriptional modification]. 3 58

Two types of particles were isolated during purification of rotavirus. Dense (D) particles have a density of 1.38 in CsCl and exhibit spontaneously a fully active endogenous transcriptase. Light (L) particles (density of 1.36 in CsCl) need to be treated with chelating agents to show a polymerase activity. The activation process of L particles was studied under strictly controlled monovalent, divalent, and hydrogen ion concentrations. These experiments demonstrate that i) activation is not affected by the ionic strength ii) activation occurs only at a pH higher than 7.1 iii) a low concentration of chelating agent (40 muM EDTA) is sufficient to activate the enzyme. Treatment of particles with EGTA, which chelates selectively Ca2+, leads to unmasking even in the presence of magnesium, indicating that the concentration of free calcium ions plays a major role in the activation process. Various glycosidases, detergents, and chelating agents were tested in respect to unmasking properties. Of these compound only chelating agents turned out to be efficient. Following activation, two glycopeptides were solubilized. These glycopeptides have an apparent molecular weight of 34,000 and 31,000 daltons and react with concanavalin A. The role of Ca2+ upon the stability of virus particles, and the activation of the endogenous transcriptase in vitro and in the infected cells is discussed.
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PMID:Activation of rotavirus RNA polymerase by calcium chelation. 4 4

The in vivo binding of N-hydroxy acetylaminofluorene (N-OH AAF) to rat liver DNA was studied in hetero- and euchromatin fractions prepared by sedimentation through sucrose gradients. The greater transcriptional capacity of the slowly sedimenting (euchromatin) fractions was confirmed by their enhanced incorporation of radioactive precursors into RNA in vivo and their increased template activity for in vitro RNA synthesis by purified RNA polymerase. N-OH AFF was bound in 4- to 5-fold greater amounts to euchromatin DNA than to heterochromatin 2 h after a single injection of the compound. However, the bound carcinogen appeared to be eliminated more rapidly from euchromatin than from heterochromatin by DNA repair processes.
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PMID:Binding of N-hydroxy acetylaminofluorene to eu- and heterochromatin fractions of rat liver in vivo. 4 28

Two sheep choroid plexus cell cultures were maintained and propagated for 413 days since being infected with strain K796 visna virus. The majority of the cells in these cultures contained visna virus-specific antigen on days 93 and 105 after infection. Reverse transcriptase-like activity similar to that present in visna virus preparations was obtained from these cultures when very little plaque-forming virus was being synthesized. The persistently infected cultures are resistant to the cytopathic effect which occurs in uninfected cultures upon exposure to visna virus. Persistently infected cells require more time than uninfected cells to become confluent. Less than 0.02 percent of the persistently infected sheep choroid plexus cells form macroscopic colonies within 14 days, whereas 20 to 30 percent of the cells from uninfected cultures form macroscopic colonies within this time.
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PMID:Long-term Visna virus infection of sheep choroid plexus cells: initiation and preliminary characterization of the carrier cultures. 4 11

9-O-methyloximd erythromycin A and its analogue inhibited reverse transcriptase and blocked focus formation of Rous sarcoma virus. These chemicals inhibited neither DNA-dependent DNA polymerase nor DNA-dependent RNA polymerase from bacterial sources. However, they inhibited reverse transcriptase with an apparently differnt mechanism than that by rifamycin ABDP.
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PMID:Oxime derivatives of erythromycin: inhibitors of Rous sarcoma virus reverse transcriptase activity and focus formation. 4 82

The proportion of cells absorbing trypan blue (tb-+ character) can be used to measure the late c.p.e. of wild-type poliovirus (ts-+. tb-+), which was the same at restrictive (39-2 to 39-6 degrees C) or permissive (37 degrees C) temperatures. Of twenty ts mutants, seven showed normal c.p.e. at 37 degrees C but were defective in C.P.E. (TB) AT 39-5 degrees C; all seven tb mutants have previously been shown (Cooper et al. 1971) to give evidence of a primary defect in replicase 1 activity (to make the complementary or minus strand of virus RNA). The remainder (tb-+) have all previously been shown to give evidence of a primary defect either in replicase II activity (to make progeny plus strands) or in structural protein. Thus, the late c.p.e. is dependent on a product of the replicase I gene, of which the in vivo effector is probably double-stranded RNA. Late c.p.e. is not caused by prevention of host protein, RNA or DNA synthesis and is not necessarily correlated with lysosomal enzyme release. The tb mutants were also defective in inducing early changes in chromatin (chr) and in prevention of thymidine incorporation (pti), but the tb and pti/chr characters are probably independent expressions of replicase I activity. Virus growth does not depend on repression of DNA synthesis. Poliovirus represses the activities of host DNA-dependent RNA polymerase I and II to an equal extent. There is no evidence that repression of DNA or RNA synthesis results from direct interaction of virus protein with the DNA.
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PMID:Poliovirus temperature-sensitivie mutants defective in cytopathic effects are also defective in synthesis of double-stranded RNA. 4 94

In search of an anti-transcriptase, antibody was raised in rabbits to partially purified, soluble NS protein present in cytoplasmic extracts of cells infected with the Indiana serotype of vesicular stomatitis (VSInd) virus. This antiserum gave specific reactions of identity by agar immunodiffusion with both cytoplasmic and virion NS protein. NS antiserum also preferentially precipitated NS 3-H-labeled protein from infected cytoplasmic extracts, whereas anti-whole VSInd virion serum also precipitated N 3-H-labeled protein from extracts both of infected cytoplasm and virion nucleocapsids. Transcriptase activity of VSInd cytoplasmic or virion-derived nucleocapsids was effectively inhibited by ribonuclease-free immunoglubulin prepared from homologous NSInd antiserum or from anti-whole vesicular stomatitis virus serum. Transcriptase activity of heterologous New Jersey serotype (VSNJ) nucleocapsids and virions was not appreciably affected by anti-NSInd or by anti-whole VSInd virion gamma globulin. Anti-NS gamma glubulin immediately switched off RNA synthesis by actively transcribing VSInd nucleocapsids, a finding which suggests that NS antibody inhibits RNA chain elongation.
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PMID:Inhibition of viral transcriptase by immunoglobulin directed against the nucleocapsid NS protein of vesicular stomatitis virus. 4 40


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