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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)

The transcription of freshly prepared nuclei and lysates from rat liver is stimulated by exogenous RNA polymerase B from calf thymus to an insignificant extent only. This also holds for chromatin isolated from nuclei lysates by separation on a Sepharose 4 B column. After removal of histone H1 by pretreatment with 0.2 M ammonium sulphate no further stimulation by added RNA polymerase has been found. If, however, the incubation time was extended, or the nuclei had been kept frozen at -20 degrees C for some time before use, a significant increase in RNA synthesis by the added RNA polymerase was obtained. In the freshly prepared nuclei as well as in the undamaged chromatin the template capacity was highly restricted. This can be seen from the fact that after pretreatment of the chromatin with 0.4 M ammonium sulphate the RNA synthesis was stimulated about 13fold.
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PMID:Transcriptional capacity of rat liver nuclei and of isolated chromatin at different ammonium sulphate concentrations. 70 21

Three peaks of DNA-dependent RNA polymerase (RNA nucleotidyltransferase) activity are resolved by chromatography of a sonicated yeast cell extract on DEAE-Sephadex. The enzymes, which are named RNA polymerases I, II, and III in order of elution, show similar catalytic properties to the vertebrate class I, class II, and class III RNA polymerases, respectively. Yeast RNA polymerase III is readily distinguished from yeast polymerase I by its biphasic amnonium sulfate activation profile with native DNA templates, greater enzymatic activity with poly[d(I-C)] than with native salmon sperm DNA, and distinctive chromatographic elution positions from DEAE-cellulose (0.12 M ammonium sulfate) compared with DEAE-Sephadex (0.32 M ammonium sulfate). The three yeast RNA polymerases also show significant differences in alpha-amanitin inhibition. RNA polymerase II is the most sensitive (50% inhibition at 1.0 mug of alpha-amanitin per ml). Contrary to the results for vertebrate systems, yeast polymerase I can be completely inhibited by alpha-amanitin at high concentrations (50% inhibition at 600 mug/ml) while yeast RNA polymerase II BEGINS TO SHOW SIGNIFICANT INHIBITION ONLY AT CONCENTRATIONS EXCEEDING 1 MG/ML. Therefore, yeast RNA polymerases I and III show a pattern of alpha-amanitin sensitivity that is the reverse of that seen for the analogous vertebrate RNA polymerases.
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PMID:Transcription in yeast: alpha-amanitin sensitivity and other properties which distinguish between RNA polymerases I and III. 77 76

Three peaks of DNA-dependent RNA polymerase (EC 2.7.7.6) activity were resolved when the enzyme was prepared from the isolated macronuclei of Tetrahymena pyriformis GL(amicronucleate strain) and chromatographed on DEAE-Sephadex A25. They were eluted at around 0.05, 0.15, and 0.2 M of ammonium sulfate, and termed TIa, TIb, and TII, respectively. All three enzymes transcribed heat-denatured DNA more efficiently, especially the peak TII, detecable only when heat-denatured DNA was used as a template. Further characterization of each enzyme, after they were rechromatographed on DEAE-Sephadex, demonstrated the similarity in many respects of TIa and TIb, and the distinct nature of the TII enzyme. TIa, TIb, and TII were all insensitive to rifampicin, while only TII was substantially inhibited by alpha-amanitin. On the other hand, the activity of TII was progressively lowered by increasing the concentration of ammonium sulfate in the assay mixture, a finding incompatible with those obtained thus far. It is concluded from the data that the Tetrahymena polymerase is of eukaryotic and not of bacterial type in spite of the findings indicating the bacterial nature of this organism.
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PMID:DNA-dependent RNA polymerase from a protozoan, Tetrahymena pyriformis. Extraction and partial characterization. 80 68

Antibody directed against rho factor from vegetative Bacillus subtilis was prepared by immunizing a rabbit with denaturated rho polypeptide isolated by electrophoresis of partially purified DNA-dependent RNA polymerase on a sodium dodecyl sulfate-polyacrylamide slab gel. Antiserum to rho reacted specifically with native rho polypeptide but not with core RNA polymerase as judged by complement fixation and by an immunodiffusion assay. Anti-rho antibody also inhibited the ability of rho to stimulate transcription of phage phie DNA but failed to inhibit transcription of poly(dA-dT) by core enzyme. Specific antibody was also raised against a mixture of the beta and beta' subunits of RNA polymerase purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The effect of the anti-rho gamma-globulin on the transcription of phage phie DNA by RNA polymerase in crude extracts of vegetative and sporulating cells was examined. Anti-rho antibody markedly inhibited the transcription of phage DNA by RNA polymerase partially purified from vegetative bacteria by ammonium sulfate fractionation but had little effect on transcription of the phage DNA template by enzyme from sporulating cells. Addition of purified rho to a vegetative extract that had been depleted of rho by treatment with the anti-rho antibody restored active transcription of phage DNA. However, addition of purified rho to an antibody-treated extract of sporulating cells had little effect on phie RNA synthesis. These findings suggest that sporulating cells contain a component that interferes with the activity of the rho subunit of RNA polymerase.
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PMID:Antibody directed against Bacillus subtilis rho factor purified by sodium dodecyl sulfate slab gel electrophoresis. Effect on transcription by RNA polymerase in crude extracts of vegetative and sporulating cells. 81 Apr 88

The activities of RNA polymerases I and II have been measured in 3T6 during the transition from the resting to growing state by solubilization of the enzymes followed by chromatography on DEAE-Sephadex columns. The activity of RNA polymerase II remains unchanged during the first 12 h after serum stimulation while the activity of RNA polymerase I increases and closely parallels the increased activity seen in isolated nuclei. Compared to enzyme from resting cells. RNA polymerase I from serum stimulated cells elutes at a lower ammonium sulfate concentration on DEAE-Sephadex chromatography and its activity shows distinctly different dependencies on the concentration of ammonium sulfate and magnesium ion. These observations are discussed in relation to the possible mechanism by which 3T6 regulates the synthesis of preribosomal RNA.
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PMID:Solubilized DNA-dependent RNA polymerase activities in resting and growing fibroblast. 83 13

Two major forms of RNA polymerase were partially purified from calf thyroid nuclei. Type I showed greatest activity in 30 mM(NH4)2SO4, transcribed native DNA best and was resistant to the inhibitor alpha-amanitin. Type II showed greatest activity in 100 mM(NH4)2SO4, transcribed denatured DNA template best and was sensitive to low concentrations of alpha-amanitin...
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PMID:Effect of thyrotropin on ornithine decarboxylase and of polyamines on RNA polymerase in the thyroid. 83 73

DNA-dependent RNA polymerases were extracted from rat uterine tissue, partially purified and resolved by DEAE-Sephadex chromatography. RNA polymerases I, II, IIIA, and IIIB eluted at the characteristic ammonium sulfate concentrations of 0.15, 0.28, 0.34, and 0.42 M, respectively. The sensitivity of each peak of polymerase to alpha-amanitin was examined and was shown to be essentially identical to the three classes of RNA polymerases in other mammalian systems. RNA polymerase I was insensitive to high levels of alpha-amanitin, RNA polymerase II was sensitive to low concentrations of alpha-amanitin (50% inhibition at 0.006 mug/ml) and RNA polymerases IIIA and IIIB were sensitive to high concentrations of alpha-amanitin (50% inhibition at 18 mug/ml). The alpha-amanitin sensitivity curve of total RNA synthesis measured in isolated nucleo demonstrated that the activity of each class of RNA polymerase could be quantitated in uterine nuclei. Thus the initial decrease in activity at low concentrations of alpha-amanitin (50% inhibition at 0.005 mug/ml) was attributed to the inhibition of RNA polymerase II activity, the second decrease in activity at higher concentrations of alpha-amanitin (50% inhibition at 15 mug/ml) was attributed to the inhibition of RNA polymerase III activity, and the activity which was resistant to the highest alpha-amanitin concentration tested was attributed to RNA polymerase I activity. When estradiol was given to immature rats 6 h before killing both RNA polymerases I and III levels in nuclei were increased significantly over the control values. The time course of these changes demonstrated that the increases in RNA polymerases I and III were first evident between 1.5 and 3 h following hormone treatment. Significantly, these increases in polymerase I and III in nuclei parallel the published increases for rRNA and tRNA synthesis following hormone treatment. However, the amount of RNA polymerase I and III was not altered upon extraction, suggesting that these changes are due to the alteration in chromatin template activity. Both estradiol and estriol produced identical increases in uterine RNA polymerase I and III 6 h after treatment.
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PMID:Hormonal control of transcription in the rat uterus. Stimulation of deoxyribonucleic acid-dependent RNA polymerase III by estradiol. 83 97

RNA biosynthesis catalyzed with DNA-dependent RNA polymerase was demonstrated in the reconstructed system containing isolated lymphocyte nuclei, Mg2+ or Mn2+ salts, ammonium sulphate, in the presence of four nucleosidetriphosphates. Both the Mg2+ and Mn2+-dependent forms of this enzyme were revealed in the nuclei of normal lymphocytes and those of patients suffering from melanoma, carcinoma of the lung and sarcoma. The activities of both forms of RNA-polymerase were greater in the nuclei of the lymphocytes from sick individuals than in the normal analogues. DNA-dependent RNA-polymerase sensitivity to dexamethasone and PHA of the nuclei of lymphocytes obtained from patients with carcinoma of the lung, melanoma, and sarcoma was decreased in comparison with the normal.
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PMID:[Sensitivity of the lymphocyte RNA-synthesizing system of patients with different malignant neoplasms to phytohemagglutinin and dexamethasone]. 85 72

A simplified method is described for the large-scale preparation of a highly purified DNA-dependent RNA polymerase B from calf thymus. The method includes homogenization and lysis of the tissue, chromatography on DEAE-cellulose, phosphocellulose, hydroxylapatite-Sephadex G-10 and, once again, phosphocellulose. The procedure avoids the preparation of nuclei, the use of sonication, ammonium sulphate precipitations and dialysis steps and needs no ultracentrifugation.
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PMID:An improved method for the preparation of the DNA-dependent RNA polymerase B from calf thymus. 87 42

Nuclei from seminal vesicle epithelium of adult guinea pigs were isolated in hypertonic sucrose solution. The incorporation of [3H]UTP by the isolated nuclei into acid-precipitable products was studied. Incorporation required ATP, GTP, CTP, UTP, and Mg+2. It was inhibited by addition of actinomycin D, deoxyribonuclease, or pyrophosphate to the reaction mixture. Thus, incorporation of [3H]UTP by isolated nuclei had the same characteristics that have been demonstrated for the reactions catalyzed by nuclear RNA polymerases. Using alpha-amanitin as a metabolic tool, we established concentrations of (NH4)2SO4. Mg+2, and nucleotides that give maximum assayable activities of nuclear RNA polymerases I and II. When the activities of polymerases I and II were measured in isolated seminal vesicle nuclei of guinea pigs that had been castrated 4 days earlier, a marked decrease in activities was found relative to control values (nuclei from intact animals). No further decrease was found 8 days after castration. Diminished accessibility to the nuclear DNA template and a decrease in the concentration of RNA polymerase molecules seemed to be responsible for the observed effects of castration on activities of RNA polymerases. An increase in ribonuclease activity did not seem to be responsible for the effects of castration. Activities of the enzymes did not change 2, 3, or 4 hours after intraperitoneal injection (2 mg/kg body weight) of each of five different androgens. Similarly, a single intraperitoneal injection of testosterone did not restore enzyme activity of polymerade I or II at any time during the first 24-hour period after hormone administration.
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PMID:RNA polymerase activities in isolated nuclei of guinea pig seminal vesicle epithelium: influence of castration and androgen administration. 90 9


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