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)

The structural relationships of S-II, S-II', and S-I(b) stimulatory proteins of RNA polymerase II purified from Ehrlich ascites tumor cells were investigated. From analysis of the amino acid compositions and tryptic peptide maps of these proteins labeled with radioiodinated Bolton-Hunter reagent, it was concluded that S-I(b) is a part of S-II located at either the amino- or carboxyl-terminal and that only this region mainly contains radioiodinatable amino acid residues when labeled using 125I. On chymotryptic digestion, S-II was cleaved to 21- and 18-kDa fragments in the presence of DNA. The 21-kDa fragment was found to be sufficient for stimulation of RNA polymerase II. It was suggested that S-II' is formed by phosphorylation of S-II in the domain containing the 18-kDa fragment.
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PMID:Structural relationships of the three stimulatory factors of RNA polymerase II from Ehrlich ascites tumor cells. 403 23

Ten ribonucleic acid (RNA) tumor viruses grown in five different host cell species and three non-oncogenic viruses from three different virus groups have been examined for ribonuclease H content. Three different substrates were used to assay ribonuclease H: calf thymus [(3)H]RNA-deoxyribonucleic acid (DNA) hybrid prepared with denatured calf thymus DNA and Escherichia coli DNA-directed RNA polymerase, (3)H-polydenylic acid [(3)H-poly(A)] complexed to polydeoxythymidylic acid [poly(dT)], and (3)H-polyuridylic acid [(3)H-poly(U)] complexed to polydeoxyadenylic acid [poly(dA)]. All ten RNA tumor viruses contained ribonuclease H activity which degraded the RNA of both the calf thymus hybrid and poly(A)-poly(dT), whereas only the ribonuclease H in the Moloney strain of murine sarcoma-leukemia virus and in RD-feline leukemia virus hydrolyzed the RNA strand of poly(U)-poly(dA). No appreciable ribonuclease H activity was detected in influenza, Sendai, or vesicular stomatitis virus. The ribonuclease H and RNA-directed DNA polymerase activities in Moloney murine sarcoma-leukemia virus were inseparable by phosphocellulose chromatography or glycerol gradient centrifugation, but appeared to be partially separated by diethylaminoethyl-cellulose chromatography.
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PMID:Ribonuclease H: a ubiquitous activity in virions of ribonucleic acid tumor viruses. 411 67

Assays are described that permit one to distinguish the reverse transcriptase of RNA tumor viruses from known normal cellular DNA-instructed DNA polymerases. Template responses of purified reverse transcriptase were compared with those of similar preparations of the DNA polymerase I of Escherichia coli and of calf-thymus polymerase. All three enzymes responded well to the synthetic duplexes poly(dT).poly(A), poly(U).poly(A), and poly(dT).poly(dA). Hence, these duplexes can detect, but cannot distinguish reverse, transcriptase from the known normal DNA polymerases. However, certain oligomer-homopolymer complexes serve as excellent distinguishing agents. The reverse transcriptase responds very well to (dT)(10).poly(A) and very poorly to (dT)(10).poly(dA), whereas both cellular DNA polymerases do not exhibit this behavior.Purified single-stranded RNA also serves as a diagnostic device, since only reverse transcriptase gives a detectable response. To be definitive, a positive response to RNA must be accompanied by a demonstration via molecular hybridization that the DNA product is complementary to the RNA and not to some minor DNA contaminant.
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PMID:Distinguishing reverse transcriptase of an RNA tumor virus from other known DNA polymerases. 433 48

Synthesis of Rous sarcoma virus RNA was examined in vitro with a new assay for radioactive virus-specific RNA. Nuclei from infected and uninfected cells were incubated with ribonucleoside [alpha-(32)P]triphosphates, Mn(++), Mg(++) and (NH(4))(2)SO(4). Incorporation into total and viral RNA proceeded with similar kinetics for up to 25 min at 37 degrees . About 0.5% of the RNA synthesized by the infected system was scored as virus-specific, compared to 0.03% of the RNA from the uninfected system and 0.005% of the RNA synthesized by monkey kidney cell nuclei. Preincubation with DNase or actinomycin D completely suppressed total and virus-specific RNA synthesis. alpha-Amanitin, a specific inhibitor of eukaryotic RNA polymerase II, completely inhibited virus-specific RNA synthesis, while reducing total RNA synthesis by only 50%. We conclude that tumor virus-specific RNA is synthesized on a DNA template, most probably by the host's RNA polymerase II.
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PMID:In vitro synthesis of Rous sarcoma virus-specific RNA is catalyzed by a DNA-dependent RNA polymerase. 436 1

A cell-free system for nuclear-directed transcription has been developed that gives prolonged synthesis in the presence of cytoplasm. The nuclear and cytoplasmic components have been prepared from Krebs II ascites tumor cells for most experiments but further observations indicate that components prepared from other cell types may be used. After an initial 5- to 10-min period of relatively rapid RNA synthesis a linear rate ensues for 2-3 hr. In the absence of cytoplasm no net RNA synthesis occurs after the initial 10-min period. Experiments with alpha-amanitin suggest that about half of the cell-free synthesized RNA is made by RNA polymerase II, the enzyme believed to be responsible for messenger synthesis in vivo.The conditions used for RNA synthesis were derived from conditions found to be optimal for protein synthesis that proceeds linearly for 2-3 hr. It has not yet been possible to demonstrate the synthesis of protein from cell-free synthesized RNA in this system. A major problem here is that isolated nuclei, even when carefully washed, contain a great deal of translatable RNA.
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PMID:Prolonged transcription in a cell-free system involving nuclei and cytoplasm. 452 63

1. Extracts prepared from tumours of the mouse colon induced by 1,2-dimethylhydrazine were considerably more active in catalysing the methylation of tRNA than were extracts from normal colon. The enhanced activity was observed when both unfractionated ;methyl-deficient' tRNA and purified tRNA preparations from yeast and bacteria were used as substrates for methylation. 2. The methylated bases produced in these reactions were identified. There were no differences between the products of the reaction catalysed by extracts of tumour and normal colon. 3. The increased activity of tRNA methylases was not due to the presence in the extracts of stimulatory or inhibitory molecules of low molecular weight such as polyamines or S-adenosylhomocysteine. 4. Other enzymes concerned with tRNA metabolism (RNA polymerase, ATP-tRNA adenylyltransferase, aminoacyl-tRNA ligases) were also increased in activity in the tumour tissue. 5. The extent of methylation of a limiting amount of tRNA was greater when tumour extracts were compared with controls, but in no case was it possible to achieve a stoicheiometric methylation of the purified tRNA preparations used as substrates, and the tumour extracts were not able to methylate tRNA obtained from normal mouse colon. We conclude that the tumours contained greater activities of tRNA methylases but that there was no evidence for changes in the specificity of these enzymes during neoplastic growth.
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PMID:Further investigation of the increased transfer ribonucleic acid methylase activity in tumours of the mouse colon. 459 40

Purified wound tumor virus was found to possess an associated ribonucleic acid (RNA) transcriptase. The product of transcriptase synthesis was shown to be single-stranded RNA which annealed specifically to wound tumor viral RNA.
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PMID:Ribonucleic acid transcriptase acitvity in purified wound tumor virus. 550 58

Exoribonuclease purified from Ehrlich ascites tumor cell nuclei and in intact HeLa cell nuclei is irreversibly inactivated by tow concentrations of p-bromo- and p-iodoacetamidophenyl nucleotides and by thymidine-3'-fluorophosphate. Iodoacetate, bromoacetate, and thymidine-5'-fluorophosphate do not affect the enzyme. Although p-haloacetamidophenyl nucleotides inactivate ribonucleic acid polymerase of isolated HeLa cell nuclei, thymidine-3'-fluorophosphate does not affect the activity of this enzyme in vitro.
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PMID:Irreversible inhibition of nuclear exoribonuclease by thymidine-3'-fluorophosphate and p-haloacetamidophenyl nucleotides. 581 84

An in vitro system for accurate transcription initiation by RNA polymerase II was developed using Ehrlich ascites tumor cells. Truncated DNA containing adenovirus 2 major late promoter was faithfully transcribed in this lysate, although the efficiency of transcription was lower than that in a HeLa cell lysate. Creatinephosphate greatly enhanced accurate transcription in this lysate. The transcriptions of various truncated mouse genes containing promoter regions in this lysate were tested, but the syntheses of run-off products were not clearly detected. Adenovirus 2 major late promoter was utilized more efficiently when integrated into circular plasmid DNA than when integrated into truncated DNA, as shown by S1 nuclease analysis.
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PMID:Accurate transcription initiation in an Ehrlich ascites tumor cell lysate. 609 90

Left-handed Z-DNA is favored by nucleotide sequences with alternating purines and pyrimidines. The structural basis of this preference is described, as well as the factors which stabilize Z-DNA. The most important biological factors stabilizing Z-DNA are negative supercoiling and Z-DNA binding proteins. Experiments are described which make it possible to determine the nucleotide sequences of segments which form Z-DNA through the use of specific antibodies. Parts of the plasmid pBR322 form Z-DNA upon negative supercoiling. Similarly, three segments of the SV40 simian tumor virus form Z-DNA. They are located in the transcriptional enhancer region and may function, together with Z-DNA binding proteins, in facilitating the attachment of RNA polymerase to the DNA in chromatin. This is the first specific example suggesting a role of Z-DNA in regulating transcription.
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PMID:Stabilization and detection of natural left-handed Z-DNA. 610 Oct 83


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