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)

alpha-Amanitin, an inhibitor of RNA polymerase II, given intraventricularly 6 or 24 h before training, impaired consolidation of both passive and active avoidance responses in rats. Administration of d-amphetamine sulfate (0.5 mg/kg intraperitoneally) immediately after training produced a clear-cut antiamnestic effect in alpha-amanitin-injected rats without modifying consolidation in control animals. Examination of several parameters of conditioning enabled the authors to rule out an impairment in locomotor performance of alpha-amanitin-treated rats both in training and in test sessions. The amnestic effect of alpha-amanitin and recovery by means of d-amphetamine were discussed in relation to RNA synthesis inhibition and a possible restoring effect of d-amphetamine upon alpha-amanitin-induced decrease of brain RNA content.
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PMID:Recovery of amnestic effect of alpha-amanitin by post-training administration of d-amphetamine in the rat. 89 94

DNA-dependent RNA polymerase I (or A) (nucleoside triphosphate:RNA nucleotidyltransferase, EC 2.7.7.6) was purified from Ehrlich ascites cells after solubilization from isolated nuclei. The purification was accomplished by a procedure involving initial precipitation with ammonium sulfate, following by chromatographies on DEAE-Sephadex and phosphocellulose ion exchange resins and gel filtration on Sepharose 6B. A chromatographically homogeneous enzyme was obtained which was purified about 2300-fold relative to nuclear extracts. The specific activity of the most purified enzyme fraction was 230 nmol of [3H]UTP incorporated into RNA per mg of protein in 10 min at 37 degrees C, which is similar to those reported for the highly purified RNA polymerase I from mouse myeloma and calf thymus. The elution position on Sepharose 6B gel filtration indicated a molecular weight of approx. 580 000. Analysis of the purified enzyme by polyacrylamide gel electrophoresis under nondenaturing conditions revealed only one protein band. Certain heterogeneity in the RNA polymerase I fractions was found in the early chromatographic steps, but not in the most purified fractions.
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PMID:Purification and properties of RNA polymerase I from Ehrlich ascites cells. 91 51

Chromatin isolated (pH 8.0) from soybean hypocotyl contains only RNA polymerase I activity as judged by its elution at low ionic strength (0.11 M ammonium sulfate) from DEAE-cellulose and DEAE-Sephadex, its total resistance to alpha-amanitin, and lack of preference for poly(dA-dT). The in vitro RNA product from this chromatin contains rRNA as a major component (36%) with little or no symmetry of transcription. The transcript from nuclei, where both RNA polymerases I and II are active, shows a dramatic increase in % rRNA (from 35 to 65%) when alpha-amanitin is present during synthesis. These observations suggest that plant RNA polymerase I is similar to animal RNA polymerase I in both its insensitivity to alpha-amanitin and preferential transcription of rRNA genes.
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PMID:Analysis of plant RNA polymerase I transcript in chromatin and nuclei. 94 86

DNA-dependent RNA polymerase C, partially purified from Xenopus laevis ovaries, has been resolved by DEAE-Sephadex chromatography in two forms, eluting at 0.2 M and 0.3 M ammonium sulfate, respectively. Both are sensitive to high concentrations of alpha-amanitin (200 mug/ml). Their ionic strength dependence and divalent cation requirements are indistinguishable. Quantitatively, RNA polymerase C represents the major form of RNA polymerase activity solubilized from the ovaries. Both RNA polymerases C are able to transcribe efficiently either high-molecular-weight Xenopus DNA or intact adenovirus DNA, as compared to nicked DNA. In contrast, RNA polymerase A has little activity on an intact DNA template. The salt dependence of the RNA polymerases C activity is different on the two kinds of template. Nicked DNA is efficiently transcribed up to a salt concentration of 100 mM ammonium sulfate. On intact DNA, optimal transcription is obtained at 40 mM ammonium sulfate and is inhibited by higher salt concentrations.
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PMID:DNA-dependent RNA polymerase C from Xenopus laevis ovaries. Ability to transcribe intact double-stranded DNA. 94 51

HeLa cell nuclei, isolated 17 h after infection with human adenovirus type 2 (Ad2), were treated with 200 mM ammonium sulfate. The extract (S200 fraction) contained 50 to 70% of the nonintegrated Ad2 DNA, which was in the form of nucleoprotein complexes. These complexes contained native, intact Ad2 DNA (with the exception of replicative intermediates) and could be partially purified and resolved by velocity gradient centrifugation. Using high-salt (200 mM ammonium sulfate) incubation conditions, more than 95% of the nuclear RNA polymerase activity belonged to class B. About 45% of the class B enzyme molecules bound to DNA in the nuclei (those "engaged" in RNA synthesis) were released from the nuclei in the form of Ad2 transcriptional complexes by treatment with 200 mM ammonium sulfate. At least 90% of the RNA synthesized in high salt in the nuclei or in the S200 fraction was Ad2 specific, and essentially all of this RNA was complementary to the l strand of Ad2 DNA. These findings are compatible with what is known about Ad2-specific RNA synthesis in vivo. The analysis of the RNA synthesized from partially purified transcriptional complexes supports the contention that its transcription is almost entirely asymmetric, and that the asymmetry observed in vivo is not a consequence of the rapid degradation of h-strand transcripts. The RNA synthesized in vitro in the absence of detectable RNase activity sedimented with a maximum size of 35 to 40S. Less than 5% of the nuclear or the S200 fraction RNA polymerase activity was class C when assayed under non-reinitiating conditions. Although much of the RNA synthesized by the class C enzyme was Ad2 specific, 5.5S virus-associated RNA was not the predominant product. The isolation of Ad2 DNA transcriptional complexes provides an attractive system for further characterizing the Ad2 DNA template used for transcription and for studying the regulation of the expression of the Ad2 genome during the productive infection cycle.
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PMID:Characterization of adenovirus type 2 transcriptional complexes isolated from infected HeLa cell nuclei. 95 Jun 90

Crude calf thymus DNA-dependent RNA polymerase, RNA polymerase B (ribonucleoside triphosphate: RNA nucleotidyltransferase, EC 2.7.7.6), was incubated with the tritium labeled, potent inhibitor [3H]amanin, in order to form the enzymatically inactive [3H]amanin-polymerase complex ([3H]A-P complex). Subsequent purification procedures for the [3H]A-P complex were based on radioactive assays. Phosphocellulose chromatography separated two radioactive components: PCI, the previously reported amatoxin binding protein, ABP (Brodner and Wieland, 1976), and PC II, the [3H]A-P complex. Sodium dodecyl sulfate gel electrophoresis of the complex showed the presence of a new heavy band very close to subunit B 1 and a decreased intensity of subunit band B 3. These were the only differences noted in the subunit structure of RNA polymerase B. [3H]Amanin was covalently coupled to the enzyme, affinity labeling, by a water-soluble carbodiimide and the resultant conjugate submitted to sodium dodecyl sulfate gel electrophoresis. The profile of radioactivity showed one main peak (greater than 2000 cpm) coinciding with the 550-nm absorption peak of subunit B 3 on a stained parallel gel. Since no other protein band contains any significant radioactivity, the binding site for [3H]amanin and most probably for all amatoxins is localized on the B 3 subunit SB 3.
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PMID:Identification of the amatoxin-binding subunit of RNA polymerase B by affinity labeling experiments. Subunit B3-the true amatoxin receptor protein of multiple RNA polymerase B. 95 70

RNA polymerase II from larvae of the brine shrimp, Artemia salina, was highly purified by two cycles of DEAE-cellulose chromatography followed by centrifugation through discontinuous sucrose gradients. Gradient fractions were subjected to elctrophoresis is polyacrylamide gels containing sodium dodecyl sulfate. The subunit structure of RNA polymerase II was determined by quantitative comparison of the polypeptides and enzyme activity present in each gradient fraction. The enzyme contains one copy of each of four subunits with estimated molecular weights of 170,000, 130,000, 36,000 and 24,000. The total molecular weight agrees well with the molecular weight estimated for the native enzyme by density gradient centrifugation.
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PMID:DNA-dependent RNA polymerases from Artemia salina. Subunit structure of polymerase II. 95 94

A factor stimulating RNA polymerase II from Ehrlich ascites tumor cells was purified. The final preparation appeared almost homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and had a molecular weight of 38 000. The endonuclease activity of about 10 mug of purified factor, if any was well below the 10(-5) mug equivalent of pancreatic deoxyribonuclease, indicating that the stimulation of RNA synthesis by this factor was not due to contaminating endonuclease. This factor specifically stimulated RNA polymerase II on native DNA as template and did not affect RNA polymerase I at all. The molecular size of RNA synthesized in the presence of this factor increased markedly compared with that synthetized by RNA polymerase II alone.
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PMID:Purification of a factor from Ehrlich ascites tumor cells specifically stimulating RNA polymerase II. 99 Feb 65

Two different forms of DNA-dependent RNA polymerase have been solubilized and purified from nuclei of Ehrlich ascites tumor cells. The purification procedure involves ammonium sulfate precipitation and gel filtration on Sephadex G-25. The separation of A and B activities is achieved by chromatography on DEAE-cellulose. Nuclei are prepared from cells, sensitive or resistant to daunorubicin. RNA polymerases A and B have an absolute requirement of divalent cations for activity. Native DNAs are better templates than heat-denatured DNAs for RNA polymerase A. On the contrary heat-denatured DNA is more transcribed than the native one by RNA polymerase B. The low level of transcription of total and nucleolar ascites DNAs is due to the DNA, the same results being obtained with ascites and calf thymus RNA polymerases A and B. The inhibitory action of daunorubicin on RNA polymerases A and B from Ehrlich ascites tumor cells has been studied in vitro. The same results are obtained with enzymes extracted from sensitive or resistant cells. Daunorubicin does not inhibit the binding of RNA polymerases to the DNA template, but prevents the transformation of the DNA-daunorubicin-RNA-polymerase unstable complex into the highly stable one. This inactive ternary complex has a dissociation rate faster than the stable complex formed without daunorubicin. The size of the RNA synthesized in the presence or absence of daunorubicin is the same.
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PMID:Daunorubicin inhibition of DNA-dependent RNA polymerases from Ehrlich ascites tumor cells. 99 57

DNA-dependent RNA polymerase I (or A) was purified from rat liver nucleoli. DNA was effectively removed from the solubilized enzyme with a defined concentration of polyethyleneglycol. The enzyme was purified further with successive DEAE-Sephadex and phosphocellulose column chromatography followed by glycerol gradient centrifugation. The procedure yielded an electrophoretically homogeneous enzyme with a specific activity 400 times that of the nucleolar extracts. The recovery of the activity was approximately 20%. The RNA polymerase I eluted as a single peak from DEAE-Sephadex was separated into two distinct peaks by a phosphocellulose column. The first peak eluting at about 0.12 M ammonium sulfate was designated as RNA polymerase IA and the second peak eluting at about 0.18 M as RNA polymerase IB. In normal rat liver nucleoli IA enzyme comprised approximately 20% of the total RNA polymerase I activity and the IB enzyme comprised approximately 80%. On sodium dodecyl sulfate polyacrylamide gel electrophoresis, enzyme IB contained five subunits with molecular weights of 195000 (a), 130000 (b), 65000 (c), 40000 (d), and 19000 (e) at nearly equimolar amounts. The calculated molecular weight of the enzyme (449000) agreed well with that predicted from the sedimentation coefficient of the enzyme. Enzyme IA contained identical subunits except that subunit c was absent. Preliminary studies could not demonstrate any significant differences in template specificity between IA and IB enzyme.
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PMID:Nucleolar DNA-dependent RNA polymerase from rat liver. 1. Purification and subunit structure. 100 57


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