Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Spermatogenesis is a complex developmental process which sequentially generates several different germ cell types. These cell types from rainbow trout (Salmo gairdnerii) testis were separated by sedimentation in serum albumin gradients and characterized on the basis of their physical properties, chronological appearance, and protein synthesis. The rate of RNA synthesis, the types of RNA made, and the RNA polymerase activities present were determined for each cell type. The rate of RNA synthesis decreased from a high level in spermatogonia and spermatocytes to a low level in early spermatids and was absent in late spermatids and mature spermatozoa. Newly synthesized RNA in spermatogonia and spermatocytes consisted of a variety of molecular weight species, including 18 S and 28 S ribosomal RNAs. The synthesis of high molecular weight RNAs, especially ribosomal RNAs, decreased drastically in early spermatids, leading to the synthesis of only small molecular weight RNAs. RNA polymerase I and II were present in all cell types but the activities of both showed large decreases between spermatocytes and middle spermatids. Both RNA polymerase activities were almost absent from spermatozoa. The activities of RNA polymerase I and II from unfractionated testis cells at different stages of hormone-induced spermatogenesis were quantitated by fractionation of the solubilized extract on DEAE-cellulose. Both polymerases showed major decreases in activity which began near the chronological mid-point of development. For polymerase I the decrease in activity was over 400 fold, for polymerase II over 200 fold. The number of RNA polymerase II molecules per testis cell, quantitated by the binding of [3H]amanitin to cell extracts, also decreased markedly during spermatogenesis. The reduction in polymerase II activity was accompanied by a parallel 200-fold decrease in[3H]amanitin binding. The reduction in polymerase activity appears, therefore, to be due to an actual reduction in the cellular content of RNA polymerase II molecules. These results suggest that transcription in maturing testes is regulated, at least in part, by the concentrations of the RNA polymerases.
Biochim Biophys Acta 1979 Dec 17
PMID:RNA synthesis and RNA polymerase activities in germ cells of developing rainbow trout testis. 51 81

Mutant dl 309 is a viable Ad5 deletion mutant. Whereas wild-type Ad5-infected HeLa cells contain two VAI RNA species [VAI(A) and VAI(G)] which differ by three nucleotides at their 5' ends, dl 309-infected HeLa cells contain VAI(G) but no VAI(A) RNA. Nucleotide sequence analysis indicates that dl 309 lacks two base pairs which precede the 5' end of VAI(A) by 22 nucleotides. Since the 5' ends of VAI RNAs are not processed, the 309 deletion serves to identify a portion of the sequence required for RNA polymerase III initiation. Since dl 309 grows as well as wild-type Ad5 in HeLa cells, the VAI(A) species is not essential for viral growth in these cells.
Cell 1979 Dec
PMID:A mutation which alters initiation of transcription by RNA polymerase III on the Ad5 chromosome. 51 73

We describe a method for analyzing ternary transcription complexes, of RNA polymerase, DNA and nascent RNA32 chains, by agarose gel electrophoresis. When the RNA of such complexes is 32P-labelled, a simple comparison of the DNA fluorogram with an autoradiogram identifies transcriptionally active DNA molecules and restriction fragments in any mixture. Two limitations on the method are described: 1) retardation during electrophoresis of polymerase-DNA complexes relative to their conjugate bare NA fragments; 2) failure of very large ternary complexes to enter gels. The following potential applications of the method are surveyed: transcription unit (elongation) mapping, separation of RNA molecules in a mixture of transcripts, dinucleotide primer mapping and identification of preferred template conformations.
Nucleic Acids Res 1979 Dec 11
PMID:Gel electrophoretic separation of transcription complexes: an assay for RNA polymerase selectivity and a method for promoter mapping. 53 12

Changes in RNA synthesis in liver nuclei were observed at different ages and after hypophysectomy and hormone replacement in female Sprague-Dawley rats. As determined by the incorporation of [3H]UMP into an acid-insoluble product, RNA synthesis decreased by about 75% in intact rats from 6 months to 24 months of age. This decline with age was not observed in liver nuclei from 24-month-old rats that had been hypophysectomized at 12 months and maintained on a minimal hormone-replacement therapy. Thyroid hormones and somatotropin (growth hormone) had an additive effect on RNA synthesis in liver nuclei from these hypophysectomized rats. The same hormones had no significant effect on intact, age-matched rats. With advancing age, nuclei of intact rats had an increase in the pool of free RNA polymerase and an apparent decrease in the enzyme activity bound to nuclear chromatin. There was no change in total enzyme with age. In hypophysectomized, hormone-treated rats, free RNA polymerase activity decreased and chromatin-bound activity increased. There was no difference in total nuclear RNA polymerase activity between operated or intact rats. However, the ratio of the bound to the free activity was different. These results suggest that the ability of RNA polymerase to bind to chromatin may be involved in the age-related decrease in liver nuclear RNA synthesis of intact rats.
Biochem J 1979 Dec 15
PMID:Effect of hypophysectomy on liver nuclear ribonucleic acid synthesis in aging rats. 54 57

The effect of the denaturation of homologous and calf thymus DNA on the RNA polymerase B activity purified from rat liver and spleen and Ehrlich ascites cells, was investigated in presence of either Mn2+ or Mg2+ and in presence or absence of alpha-amanitin. On the basis of the results here reported, we suggest: 1) denatured DNA is more effective than native as template for polymerase B; 2) denatured DNA template and cations might play a role in determining the extent of the reaction alpha-amanitin-polymerase B.
Boll Soc Ital Biol Sper 1979 Dec 15
PMID:[Effect of denaturation of DNA template on activity of RNA polymerase of class B]. 54 76

The effect of low concentrations of actinomycin D was investigated, using two forms of DNA-dependent RNA polymerase (A and B) purified from normal tissues and experimental tumours, in the presence either of Mn2+ or Mg2+, and homologous DNA. The A enzyme activity was strongly inhibited by the antibiotic in presence of Mg2+ and much less in presence of Mn2+. The B enzyme activity was almost suppressed in presence of both cations. The results here reported provide support that the actinomycin D induce a cellular damage of the same extent in normal and tumour tissues.
Boll Soc Ital Biol Sper 1979 Dec 15
PMID:[Effect of actinomycin D on purified DNA-dependent RNA polymerases from normal and neoplastic tissues]. 54 77

When partially purified Ehrlich ascites tumor RNA polymerase II was further purified on a column of phosphocellulose, stimulation of its catalysis of RNA synthesis by stimulatory factor S-II was greatly decreased. This decrease in sensitivity to the stimulatory factor was reversible: the enzyme eluted from phosphocellulose became sensitive to the factor when mixed with a protein fraction eluted from the phosphocellulose at high salt concentration. Evidence was obtained that this protein, named helper protein, binds, to the enzyme eluted from phosphocellulose, causing it to recover sensitivity to stimulatory factor S-II.
Biochemistry 1977 Dec 27
PMID:Protein which interacts with a stimulatory factor of RNA polymerase II of Ehrlich ascites tumor cells. 56 40

DNA-dependent RNA polymerase from Micrococcus luteus can be isolated from cell extracts after removal of an excess of nucleic acids by fractionation with ammonium sulfate, followed by two consecutive gel filtrations through agarose and chromatography on cellulose phospate. Either homogeneous holoenzyme or a mixture of core and holoenzyme is obtained in this way, as is indicated by electrophoresis in polyacrylamide gels in the absence of detergent, where core enzyme migrates ahead of holoenzyme. Homogeneous core enzyme can be isolated from holoenzyme by chromatography on DEAE-cellulose. Core enzyme contains the subunits alpha, beta and beta' previously described [U.I. Lill et al., (1975) Eur. J. Biochem. 52, 411-420] in a molar ratio of 2:1:1. Holoenzyme contains an additional subunit sigma of 80 000 molecular weight (molar subunit composition alpha2 betabeta' sigma) and two relatively small polypeptides (molecular weight 14 000 and 25 000, respectively). Subunit sigma may be isolated from holoenzyme by chromatography on DEAE-cellulose at pH 6.9 in the presence of low concentrations of glycerol. The behaviour of holoenzyme during sedimentation in a glycerol gradient at low ionic strength indicates its occurrence as a dimer of the alpha2betabeta'sigma-protomer, whereas the monomeric form is preferred by core enzyme. Holoenzyme is much more active than core enzyme in RNA synthesis on bacteriophage T4DNA as template. The activity of the latter is stimulated by isolated sigma. M. luteus sigma as well as holoenzyme enhances also the activity of core enzyme fro- Escherichia coli. The formation of a hybrid between micrococcal sigma and E. coli core polymerase is also suggested by the influence of sigma on the oligomerisation of the enzyme from E. coli.
Hoppe Seylers Z Physiol Chem 1977 Dec
PMID:Purification and characterization of the DNA-dependent RNA polymerase and its subunit sigma from Micrococcus luteus. 59 Sep 42

The rational design of antitumor and antiviral agents must ultimately take advantage of biochemical differences between normal host cells and transformed cells. The initial experiments must be performed with subcellular or cellular model systems. For the studies with arabinosyl nucleosides we have chosen those enzyme systems, synthesizing DNA and RNA; being precursor analogues, the different arabinosyl nucleosides have been added in the triphosphate state to the different DNA- and RNA polymerase assays. 1-beta-D-Arabinofuranosylcytosine-5'-triphosphate has been found to inhibit the RNA-dependent DNA polymerases (isolated from oncogenic RNA viruses) 200-fold more sensitively than viral and cellular DNA-dependent DNA polymerases. Recent results, showing that RNA-leukemia-virus-related sequences are present in DNA of some human leukemia patients might support the assumption that the efficacy of this antimetabolite in the treatment of acute leukemia is due to its, at least relative selective inhibitory activity on reverse transcriptase. 9-beta-D-Arabinofuranosyladenine-5'-triphosphate is a strong inhibitor of cellular DNA polymerases with the cytological consequence of an inhibition of cell proliferation. The clinical benefit of the compound in treatment of tumors is dependent on their levels of adenosine deaminase. The triphosphate of this compound is a 100-fold more sensitive inhibitor of the herpesvirus DNA polymerase compared to the cellular replicative DNA polymerase. In addition the analogue, incorporated into herpesvirus DNA, acts as chain terminator. These effects are the biochemical basis for the highly selective antiherpesvirus activity of this antimetabolite. The anomer 9-alpha-D-arabinofuranosyladenine-5'-triphosphate only inhibits cellular replicative DNA polymerase and has no effect on herpesvirus DNA polymerase. Consequently this agent acts only cytostatically and not antivirally. Concerning 1-beta-D-arabinofuranosyluracil and 1-beta-D-arabinofuranosylthymine no pronounced antitumor or antiviral effect is known.
Jpn J Antibiot 1977 Dec
PMID:Rational design of arabinosyl nucleosides as antitumor and antiviral agents. 61 2

The effect of cerebral ischemia on polypeptide synthesis with isolated microsomes and DNA-dependent RNA polymerase activity with isolated nuclei was investigated by occlusion of right common carotid artery of gerbils. There was a prompt decline of microsomal polypeptide synthesis already at 30 min after occlusion of the artery, and at 4--5 h the specific radioactivity (dpm per microgram protein) was 50% of the control value. At 24 h, when the animals were only slightly responsive to external stimuli, the specific radioactivity of ischemic brain was only 20% of the control value. DNA-dependent RNA polymerase activity was unaffected for 1 h, and clear suppression did not appear until 3 h after occlusion. However, the extent of suppression was similar between polypeptide synthesis and RNA polymerase activity beyond 3 h after occlusion. Although more selective vulnerability of polypeptide synthesis thus exists in cerebral ischemia, the difference between two biochemical processes was not as striking as seen in cerebral anoxia. Focal progression of cerebral ischemia to diffuse infarction in gerbils was suggested as a possible explanation for the disparity in comparison to the diffuse effect in cerebral anoxia along with the difference in the magnitude of acidosis and depletion of energy reserve.
Brain Res 1978 Dec 15
PMID:Experimental stroke in gerbils: effect on translation and transcription. 70 73


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>