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)

Isolated nuclei frommouse myeloma cells which were active in RNA synthesis did not synthesize detectable amounts of poly(A)-containing RNA. On addition of a soluble protein extract from crude nuclei, the highly purified nuclei synthesized significanamounts of poly(A)-containing RNA, as analyzed by chromatography on poly(U)-Sepharose. The poly(A) tract was totally synthesized de novo and was indistinguishable from poly(A) synthesized in vivo. Twenty per cent of the RNA polymerase II products were polyadenylated. More than 80% of the newly synthesized poly(A) was present on molecules at least partially transcribed in vitro. The transcription and polyadenylation reaction could be separated temporally and a portion (10%) of the polyadenylated RNA was released into the extra nuclear fraction. We conclude that this system carries out one RNA processing reaction, polyadenylation, faithfully.
J Biol Chem 1978 Dec 10
PMID:Polyadenylation of RNA in a cell-free system from mouse myeloma cells. 71 58

Reovirus infectivity and core-associated RNA polymerase activity were decreased by irradiation with long wavelength ultraviolet light in the presence of the 4'-substituted psoralen derivatives, 4'-aminomethyl-4,5',8-trimethylpsoralen and 4'-hydroxymethyl-4,5',8-trimethylpsoralen. Monoadduct formation occurred after photoreaction with low psoralen concentrations or brief irradiation times, and the presence of KCl or magnesium acetate had a protective effect. Under the mild reaction conditions in which 1 molecule of 4'-aminomethyl-4,5',8-trimethylpsoralen was bound covalently per 160 to 290 base-pairs, the polymerase activity was decreased by greater than 90%. At higher drug concentrations or longer times of photoreaction of reovirus cores, the viral RNA was extensively cross-linked indicating that the reovirus genome in situ is double-stranded.
J Biol Chem 1978 Dec 25
PMID:Photochemical cross-linking of reovirus genome RNA in situ and inactivation of viral transcriptase. 72 5

The hypothesis of functional hemizygosity has been examined for the alpha-amanitin resistant (AmaR, a codominant marker) locus in a series of Chinese hamster cell lines. AmaR mutants were obtained from different cell lines, e.g., CHO, DHW, M3- 1 and CHO-Kl, at similar frequencies. After fractionation of different RNA polymerase activities in the extracts by chromatographic procedures, the sensitivity of the mutant RNA polymerase II towards alpha-amanitin was determined. While all of the RNA polymerase II activity in mutant CHO and CHO-Kl lines became resistant to alpha-amanitin inhibition, only about 50% of the activity is highly resistant in AmaR mutants of CHW and M3- 1 cell lines. The remaining activity in the latter cell lines shows alpha-amanitin sensitivity similar to that seen with the wild-type enzyme. This behaviour is similar to that observed with a 1:1 mixture of resistant and sensitive enzymes from CHO cells. These results, therefore, strongly indicate that while only one functional copy of the gene affected by alpha-amanitin is present in CHO and CHO-Kl cells, two copies of this gene are functional in the CHW and M3-1 cell lines.
J Cell Physiol 1978 Dec
PMID:Evidence for variation in the number of functional gene copies at the AmaR locus in Chinese hamster cell lines. 73 Jul 80

The histology, ultrastructure, and nuclear RNA polymerase activity are described in a murine primitive neuroectodermal tumor derived by serial transplantation from a tumor originally induced with methylcholanthrene and classified as an ependymoblastoma. The light microscope and ultrastructural studies show that this tumor does not contain the distinguishing morphological features of differentiated ependymal cells which are also commonly seen in human ependymomas. One outstanding feature is the size and number of the nucleoli. The mean number of nucleoli/nucleus is 4 which is two to four times that of the normal neuroglial cell. The nucleolar diameter is about twice that found in normal neuroglial cells. The nucleolar diameter is about twice that found in normal neuroglial cells. The nuclear RNA synthesizing activity is the highest of the chemically induced animal tumors we have studied. The alpha amanitin inhibition is the lowest seen in any of these tumors which suggests that RNA polymerases inhibited by alpha amanitin contribute less to the total nuclear RNA synthesis. Adriamycin significantly inhibits the nuclear RNA polymerase activity of this tumor.
Acta Neuropathol 1978 Dec 15
PMID:Methylcholanthrene induced murine primitive neuroectodermal tumor: ultrastructure and nuclear RNA polymerase activity. 73 55

This paper describes the synthesis of O6-methyldeoxyguanosine triphosphate (m6dGTP) and its copolymerization to high molecular weight polymer with deoxycytidylic acid. The monomer, m6dGTP, was synthesized from deoxyguanosine first protected by acetylation of the sugar hydroxyls, and then chlorinated in the 6-position with POCl3. The product, 6-chloro-3',5'-di-O-acetyl deoxyguanosine, was converted to O6-methyldeoxyguanosine with sodium methoxide and phosphorylated in the 5' position with carrot phosphotransferase. Monophosphate was converted chemically to the triphosphate and copolymerized with dCTP by terminal deoxynucleotidyl transferase. The resulting template, which contained O6-methylguanine, was tested for its ability to direct RNA synthesis by bacterial RNA polymerase. The presence of O6-methylguanine was shown to lead to the misincorporation of UMP in the product polymer, thus strengthening the hypothesis that O6-methylguanine is a promutagenic base.
Biochim Biophys Acta 1978 Dec 21
PMID:Synthesis and properties of O6-methyldeoxyguanylic acid and its copolymers with deoxycytidylic acid. 73 85

Castration results in a rapid decrease in the activity of RNA polymerase I (or A) of isolated nuclei of rat prostates. The decrease was mainly ascribed to the diminution in the number of in vivo initiated RNA chains. The "free form" activity of the enzyme, however, which was estimated by the use of exogenous template and actinomycin D, increased 24 h after castration, then dropped rapidly. The administration of testosterone to castrated rats caused an increase in the activities of both RNA polymerases I and II (or B), which started 2 h and reached the maximum 12 h after the administration. No initial rise in RNA polymerase II activity was observed during the first 2 h. The administration of cycloheximide to normal rats caused a very rapid decrease of the activity of template-bound RNA polymerase I of isolated prostatic nuclei (t1/2=1.7 h), while the "free form" activity of the enzyme did not appreciably change until 3 h. The androgen-stimulated increase in the "engaged form" of the RNA polymerase I of isolated nuclei was completely abolished by the administration of cyclohexmide 60 min before killing. Based on the results obtained, the role of protein(s) with a rapid turn-over which is/are androgen-dependent and presumably participating in the control of preibosomal RNA synthesis is discussed.
J Biochem 1978 Dec
PMID:In vivo effect of androgen and cycloheximide on the RNA synthesis in isolated nuclei of rat ventral prostates. 73 1

The effect of triamcinolone acetonide on the transcriptional activity in nuclei isolated from maternal A/J mouse livers and embryonic maxillary processes (EMP) has been studied. Triamcinolone acetonide (TAC, 13 mg/kg body weight) was administered to A/J mice on day 12.5 of gestation, and the mice were sacrificed at different time periods following injection. We find a significant increase in transcription in liver nuclei, and a decrease in this activity in nuclei from embryonic maxillary processes in response to TAC at 16 to 20 hours following injection. With the drug alpha-amanitin we show that the effect of TAC on transcription in EMP cannot be due to fluctuations in the concentration of endogenous RNA polymerase B. This is further substantiated by studies on the transcription of EMP-nuclei in the presence of exogenous DNA template. Relative to controls, the data demonstrates that the concentrations of RNA polymerases A and B in EMP-nuclei remain unchanged in response to TAC. Conversely, stimulated liver nuclei result in significant increases in the concentrations of RNA polymerases A and B. We therefore propose that in embryonic maxillary processes TAC induces changes in the chromatin template which may interfere with normal development.
Teratology 1978 Dec
PMID:Induction of cleft palates: effects of triamcinolone acetonide on transcription in isolated nuclei. 74 87

1. A nucleoplasmic fraction rich in endogenous RNA polymerase II activity was isolated from rat liver nuclei and conditions were determined under which elongation of RNA molecules initiated in vivo continued at maximal rates in vitro. 2. Elongation rates in vitro were calculated to be about 0.25 nucleotide/s and there were about 7 X 10(3) RNA molecules in the process of being elongated by form-II RNA polymerase per original nucleus. 3. Evidence was obtained suggesting that transcription-dependent release of RNA polymerase II molecules from the template occurred during the incubations in vitro. 4. The nascent RNA was tightly associated with protein and banded as ribonucleoprotein in caesium salt gradients. 5. RNA molecules labelled in vitro were up to 13000 nucleotides in length, but consisted of long unlabelled chains transcribed in vivo with only short labelled sequences added in vitro, and without significant polyadenylation. 6. Hybridization of transcripts in the presence of a vast excess of DNA demonstrated that both form-II RNA polymerase and another enzyme, resistant to low alpha-amanitin concentrations, were synthesizing RNA molecules complementary to both reiterated and unique DNA sequences in the genome.
Biochem J 1978 Dec 15
PMID:The use of rat liver nucleoplasm for the characterization of heterogeneous nuclear ribonucleic acid synthesis in vitro. 74 48

As an effort to elucidate the control of quality and quantity of the DNA-dependent RNA polymerase in Escherichia coli, the rate of synthesis of the individual subunits was determined during shift-up and -down of nutrients. When the strain B/r grown in a succinate medium was imposed to a shift-up by adding a mixture of glucose and amino acids, rapid rise was observed of the differential rates of the synthesis of alpha, beta and beta' subunits, the constituents of core enzyme, leading to the increase of core polymerase concentration. The differential rates decreased thereafter to the level characteristic of the post-shift rate of cell growth. Compared to the strain B/r, the adaptation was slow in the strain K12 W3350. On the other hand, upon transfer of the strain B/r from a glucose-amino acids medium to a glucose medium lacking amino acids, the differential rate of core polymerase synthesis decreased rapidly and then regained the rate characteristic of the new growth rate. Similar control was also observed on the rate of ribosomal protein synthesis suggesting the coordinate expression of genes for the core polymerase subunits and ribosomal proteins. Thus, the intracellular concentration of RNA polymerase as well as of ribosomes might be one of the most important factors that affect the rate of bacterial growth. The rate of alpha subunit synthesis, however, exhibited little change during the shift-up but a considerable decrease was observed during the shift-down.
Mol Gen Genet 1975 Dec 23
PMID:Biosynthesis of RNA polymerase in Escherichia coli. II. control of RNA polymerase synthesis during nutritional shift up and down. 76 37

Studies on the rate of synthesis of the beta and beta' subunits of RNA polymerase in haploid strains of Escherichia coli K12 containing poorly-suppressed rif degrees am mutations provide conclusive evidence that synthesis of at least these two subunits is regulated.
Mol Gen Genet 1975 Dec 30
PMID:Induction of RNA polymerase synthesis in Escherichia coli. 76 46


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