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)

Labeling of RNA in isolated HeLa cell nuclei in vitro reveals an abundance of short RNA chains made by RNA polymerase II. These short chains were initiated prior to isolation of the nuclei. The short abundant chains are increased in amount in nuclei isolated from cells treated with 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB). Kinetic evidence indicates that the bulk of the putative heterogeneous nuclear RNA (hnRNA) precursor molecules that are terminated early in vivo are terminated approximately 100-300 nucleotides from sites of initiation. DRB increases the frequency of early termination, but there is a fraction of hnRNA precursor molecules whose elongation is not affected by DRB. Heparin is useful in studies of hnRNA transcription in isolated nuclei because it enhances chain elongation.
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PMID:Early termination of heterogeneous nuclear RNA transcripts in mammalian cells: accentuation by 5,6-dichloro 1-beta-D-ribofuranosylbenzimidazole. 29 79

The influence of cortisol and prolactin on casein gene expression in the mammary gland of lactating BALB/c mice was measured by using a specific cDNA probe to 15S casein mRNA (cDNAcsn). Casein mRNA (mRNAcsn) level in the mammary gland was decreased by 85% 5 days after adrenal ablation, but then was increased 4.4-fold 12 hr after a single injection of hydrocortisone-21-acetate. An 80% decrease in serum prolactin level, induced by the prolactin inhibitor 2-bromo-alpha-ergocryptin (CB-154), did not alter the level of mRNAcsn in the gland. Specific transcription of the casein gene in nuclei isolated from lactating mammary glands was measured by cDNAcsn hybridization to the in vitro synthesized Hg-CTP-containing RNA (Hg-RNA), which was purified by SH-agarose chromatography. The level of the mRNAcsn in Hg-RNA synthesized in the isolated nuclei was 0.09% and this was decreased 85% by alpha-amanitin, indicating that the mRNAcsn sequences in the Hg-RNA were the products of RNA polymerase II-directed DNA-dependent RNA synthesis. Transcription of the mRNAcsn in isolated nuclei was decreased by 70% 5 days after adrenalectomy and a single injection of the glucocorticoid then increased the transcription level 2-fold at 6 hr. Essentially no alteration of the level of transcription was detectable in mammary nuclei isolated from lactating mice with 80% decreased serum prolactin level, induced by CB-154 treatment. The results thus demonstrate a glucocorticoid involvement on the modulation of casein gene expression at the transcriptional level of control.
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PMID:Glucocorticoid modulation of casein gene transcription in mouse mammary gland. 29 34

A procedure for the simultaneous purification of RNA polymerases I, II, and III from Saccharomyces cerevisiae is described. High yields of each enzyme activity are obtained, allowing the preparation of approximately 10 mg of polymerase I, 25 mg of polymerase II, and 12 mg of polymerase III from 1.2 kg of cells (wet weight). Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate indicates RNA polymerase I contains polypeptides with molecular weights 185 000, 137 000, 41 000, 35 000, 28 000, 24 000, 20 000, 16 000, 14 500, and 12 300; RNA polymerase II contains subunits with molecular weights 170 000, 145 000, 41 000, 33 500, 28 000, 24 000, 18 000, 14 500, and 12 500; and RNA polymerase III contains polypeptides with molecular weights 160 000, 128 000, 82 000, 53 000, 41 000, 37 000, 34 000, 28 000, 24 000, 20 000, 14 500, and 10 700.
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PMID:Isolation of ribonucleic acid polymerases I, II, and III from Saccharomyces cerevisiae. 31 51

Mercurated UTP was used as a substrate for RNA polymerases in the in vitro transcription of chromatin so that newly synthesized RNA could be efficiently separated from endogenous chromatin RNA by means of sulfhydryl-Sepharose affinity chromatography. Utilizing this technique, it was possible to examine the effect of varying enzyme to DNA ratios on the transcription of specific genes from chromatin. For both Escherichia coli RNA polymerase and wheat germ RNA polymerase II, lowering the enzyme to DNA ration resulted in an increase in the percentage of ovalbumin mRNA sequences transcribed from chick oviduct chromatin. Similar results were also obtained for the transcription of the globin gene from chick reticulocyte chromatin. On the other hand, transcription of the globin gene from oviduct chromatin or the ovalbumin gene from reticulocyte chromatin or deproteinized chick DNA was not significantly affected by varying enzyme to DNA ratios. These results indicate that preferential transcription of certain chromatin genes relative to total RNA synthesis can occur and that this process is dependent on the presence of chromosomal proteins. Utilizing a cDNA probe complementary to the anticoding strand of the ovalbumin gene, the degree of asymmetry of the in vitro transcription of this gene was also examined. The percentage of ovalbumin RNA sequences homologous to the anticoding strand was not significantly affected when the enzyme to DNA ratio was lowered 16-fold. Since the percentage of coding ovalbumin mRNA sequences increased more than 6-fold over the same range, the percentage of asymmetric transcription of this gene increased. At the lowest enzyme to DNA ratio tested, the transcription of the ovalbumin gene from oviduct chromatin was almost totally asymmetric and, thus, closely resembled the pattern of gene transcription characteristic of the in vivo state.
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PMID:Effect of estrogen on gene expression in the chick oviduct. 32 57

Partially purified yeast RNA polymerases (RNA nucleotidyltransferases) initiate DNA synthesis by yeast DNA polymerase (DNA nucleotidyltransferase) I and to a lesser extent yeast DNA polymerase II in the replication of single-stranded DNA. The enzymatic initiation of DNA synthesis on phage fd DNA template occurs with dNTPs alone and is further stimulated by the presence of rNTPs in DNA polymerase I reactions. The presence of rNTPs has no effect on the RNA polymerase initiation of the DNA polymerase II reaction. RNA polymerases I and III are more efficient in initiation of DNA synthesis than RNA polymerase II. Analyses of the products of fd DNA replication show noncovalent linkage between the newly synthesized DNA and the template DNA, and covalent linkage between the newly synthesized RNA and DNA.
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PMID:Enzymatic initiation of DNA synthesis by yeast DNA polymerases. 32 62

To probe the structural change in the genome of the differentiating germ cell of the maturing rooster testis, the chromatin from nuclei at various stages of differentiation were transcribed with prokaryotic RNA polymerase from Escherichia coli or with eukaryotic RNA polymerase II from wheat germ. The transcription was performed under conditions of blockage of RNA chain reinitiation in vitro with rifampicin or rifampicin AF/013. With the E. coli enzyme, the changes in (1) the titration curve for the enzyme-chromatin interaction, (2) the number of initiation sites, (3) the rate of elongation of RNA chains, and (4) the kinetics of the formation of stable initiation complexes revealed the unmasking of DNA in elongated spermatids and the masking of DNA in spermatozoa. In both cases the stability of the DNA duplex in the initiation region for RNA synthesis greatly increased. In contrast with the E. coli enzyme, the wheat-germ RNA polymerase II was relatively inefficient at transcribing chromatin of elongated spermatids. Such behaviour can be predicted if unmasked double-stranded DNA is present in elongated spermatids.
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PMID:Studies on sex-organ development. Changes in chromatin structure during spermatogenesis in maturing rooster testis as demonstrated by the initiation pattern of ribonucleic acid synthesis in vitro. 34 18

Using hepatic RNA polymerase I and II from either normal or N-2-hydroxy-2-acetylaminofluorene (N-OH-AAF)-treated rats or E. coli RNA polymerase, the degree of misincorporation of noncomplementary nucleotides was assessed with the synthetic templates, poly(dG-dC).poly(dG-dC) and poly (dA-dT).poly(dA-dT). The predominant base-pair transformation that was transcribed in the presence of Mg++ or Mn++ by RNA polymerase I from control or N-OH-AAF-treated animals or by E. coli RNA polymerase with poly(dG-dC).poly(dG-dC) as template was the transversion, dG-rC to dG-rA; however, transcription in the presence of Mg++ by RNA polymerase II from carcinogen-treated animals showed a statistically greater degree of the base-pair transformation, dG-rC to dG-rU. In contrast, RNA polymerase I and II from control or N-OH-AAF-treated animals transcribed the base-pair transformation, dA-rU to dA-rG, dA-rU to dA-rC and dA-rU to dA-rA to equal extents with poly(dA-dT).poly(dA-dT) as template. E. coli RNA polymerase transcribed the latter template to produce only the transversion, dA-rU to dA-rG. These results suggest that RNA polymerases are capable of miscopying synthetic DNA templates. The consequences of base-pair transformations on the fidelity of transcription after carcinogen treatment is discussed.
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PMID:Comparisons of the fidelity of transcription of RNA polymerase I and II following N-hydroxy-2-acetylaminofluorene treatment. 35 43

Transcription was determined in liver chromatin from rats fed for 6 days, an optimal (20%) or suboptimal (3%) amount of high-quality protein. Transcription by Escherichia coli RNA polymerase (EC 2.7.7.6) was lower after prolonged incubation with chromatin from rats fed 3% as compared with 20% protein. Differences were detected in the transcripts of the two types of chromatin after analysis by sucrose density gradient centrifugation. But no measurable differences were found in the melting profiles at low ionic strength of the two chromatin preparations. Transcription per milligram chromatin DNA was 25-fold higher using E. coli RNA polymerase instead of rat liver RNA polymerase II. The use of UTP as radioactive precursor in the absence of ATP, GTP and CTP resulted in a low labelling of RNA. One [lambda32P]UTP nucleotide was incorporated/8 UMP nucleotides. The product obtained was sensitive to ribonuclease treatment. In the presence of ATP, GTP and CTP [lambda-32P]UTP nucleotide incorporation was reduced and that of UMP nucleotide was increased giving a ratio of 1:188.
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PMID:Transcription of rat liver chromatin by Escherichia coli RNA polymerase: template properties after protein restriction. 36 67

Interactions between a plant RNA polymerase II and ColE1 based plasmid DNA templates have been studied. Gel electrophoresis indicates that the enzyme binds to both supercoiled and linear species. Using the totally double stranded pMB9/SmaI fragment it is shown that transcription of completely base paired DNA is ten-fold lower than that of denatured or supercoiled plasmid, and reflects the presence of fewer initiation sites. A small proportion of the transcript remains tightly bound to supercoiled templates. 3' oligodeoxycytidine extensions on pMB9/SmaI serve to promote transcription of the linear double stranded form. Using restriction kinetics it is shown that there is a small enhancement of polymerase binding at the pMB9 tetracycline promoter, but that the selectivity of binding at this locus is lower than for the natural bacterial polymerase.
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PMID:The interaction of RNA polymerase II from wheat with supercoiled and linear plasmid templates. 37 Jul 89

The DNA-dependent RNA polymerase I (or A) from the lower eukaryote Aspergillus nidulans has been purified on a large scale to apparent homogeneity by homogenizing the fungal hyphae in liquid nitrogen, extraction of the enzyme at high salt concentration, precipitation of RNA polymerase activity with polymin P (a polyethylene imine), elution of the RNA polymerase from the polymin P precipitate, ammonium sulphate precipitation, molecular sieving on Bio-Gel A-1.5m, binding to ion-exchangers and DNA-cellulose affinity chromatography. By this procedure 1.6 mg of RNA polymerase I can be purified over 2000-fold from 500 g wet weight of starting material with a yield of 30--35%. The isolated RNA polymerase I is stable for several months at -20 degrees C. The subunit compostion has been resolved by polyacrylamide gel electrophoresis on two-dimensional gels, using either non-denaturing of 8 M urea (pH 8.7) cylindrical gels in the first dimension and sodium dodecyl sulphate slab gels in the second dimension. The putative subunits have molecular weights of 190,000, 135,000, 63,000, 62,000, 43,000, 29,000, (28,000), 16,000 and probably 13,000 and 12,000. Two distinct forms of RNA polymerase I (Ia and Ib) have been resolved by DEAE-Sephadex A-25 chromatography showing ample differences in enzymatic properties and subunit pattern. Additional information is given on RNA polymerase II (or B) which appears to be highly insensitive to alpha-amanitin at concentrations up to 400 micrograms/ml.
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PMID:RNA polymerase from the fungus, Aspergillus nidulans. Large-scale purification of DNA-dependent RNA polymerase I (or A). 38 Sep 97


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