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)

Although many researchers have reported that RNA synthesis in the ovary is enhanced by gonadotropin treatment, there are only a few papers concerning the character of newly synthesized RNA after gonadotropin treatment. In this paper, the RNA synthesized in the ovary of immature rats after HCG treatment was qualitatively studied. Immature female Sprague-Dawley rats were administered with 0.3 mc per rat of 3H-uridine at a certain time interval after injection of HCG (10 iu/rat) and the ovaries were subsequently isolated after 15, 30 or 60 minutes. RNA was extracted from the homogenate of the ovaries according to the hot phenol method after Scherrer and Darnell. The 3H-RNA thus extracted was treated with electrophoretically purified DNase to break down and remove DNA that mingled with it. The RNA solution ultimately obtained was analysed on a 3-20% sucrose gradient. The different fractions thus separated were then subjected to measurement of radioactivity and optical density at 260 mmug. The RNA extracted from the ovary of immature untreated rat labeled with 3H-uridine for 15 minutes showed a flat pattern of radioactivity from the top to the bottom fractions with low radioactivity. Otherwise, when labeled for one hour, the RNA showed a pattern of radioactivity like those of optical density at 260 mumu with peaks of r-RNAs and t-RNA. When the ovary was pulse-labeled with 3H-uridine for 15 minutes starting 2 hours after injection of HCG, the RNA with a large S value was synthesized and the pattern of variation in radioactivity was that of rising near the bottom fraction and declining with access to the top fraction. The results obtained by labeling for 15 minutes starting 40 hours after PMS administration were similar to those obtained in immature untreated rats. The patterns of radioactivity in RNA obtained by the labeling for 15 minutes starting 2 hours after HCG and 42 hours after PMS were similar to those starting 2 hours after only HCG injection. The patterns of radioactivity became similar to those of optical density at 260 mmu, when the ovaries were labeled for 30 or 60 minutes. From these results, it was suggested that the newly synthesized RNA 2 hours after HCG was constructed from m-RMA with rapid turn over and precursors of r-RNAs and t-RNA. This RNA synthesis was blocked by pretreatment with actinomycin but not by cycloheximide. From these results, it was suggested that enhancement in RNA polymerase activity or change in template capacity of DNA which would have an effect on RNA synthesis was not based on newly synthesized protein.
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PMID:[Studies on the RNA synthesized in the ovary of immature rats after HCG administration (author's transl)]. 5 Sep 55

Isolated rat liver nuclei were incubated under appropriate conditions in the presence of 0.5 micrograms/ml alpha-amanitin and an RNAase inhibitor prepared from cytosol fraction, together with alpha-32P-UTP or alpha-32P-CTP and three other nucleoside triphosphates. RNA extracted by an SDS-hot phenol procedure was fractionated with sucrose density gradient centrifugation followed by acrylamide gel electrophoresis. Fingerprint analysis of the in vitro synthesized "5S" RNA, which was slightly larger than mature 5S RNA on gel electrophoresis, showed that it contained all the sequences of mature 5S RNA except for the oligonucleotide at the 3' end. Instead, it contained two additional spots which were not present in mature 5S RNA. Analysis of the extra spots revealed that they were derived from the 3' end of the in vitro synthesized "5S RNA, which were sequenced tentatively as -CUUGAUGCUUoh (extra sequence underlined). The 5' end of the product was (p)pGU--. Isolated HeLa cell nuclei synthesized similar sized "5S" RNA under the same conditions. We conclude from these results that in isolated nuclei of these mammalian cells RNA polymerase III starts transcription of 5S RNA gene at the same site as the 5' end of mature 5S RNA, proceeds toward the 3' direction and stops at a site probably 8 nucleotides downstream from the 3' end of mature 5S RNA. Experiments with a short pulse and with various "chases" have demonstrated the presence of a short-lived precursor 5S RNA which is similar in size and sequence to in vitro "5S" RNA, suggesting that 5S RNA is synthesized in vivo as a longer precursor molecular as demonstrated in this in vitro system, and is rapidly processed into mature 5S RNA.
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PMID:In vitro synthesis of a 5S RNA precursor by isolated nuclei of rat liver and HeLa cells. 11 Apr 59

Human coronavirus RNA, prepared by extraction of purified virions with phenol-chloroform, consists of a major 15 to 55S class and a minor 4S class of RNA fragments. Polyadenylic acid [poly (A)] sequences are present in 15 to 55S but not in 4S RNA, suggesting different functions for each class. A stretch of poly (A) of approximately 19 adenosine monophosphate residues was obtained in sizing experiments after digesting OC-43 RNA with pancreatic and T1 ribonucleases. An OC-43 virion RNA transcriptase could not be detected with systems optimal for detecting the transcriptases of influenza and Newcastle disease virus.
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PMID:Presence of genomic polyadenylate and absence of detectable virion transcriptase in human coronavirus OC-43. 64 31

Evidence indicates that dormancy is initiated in the spores of Agaricus bisporus by two quinoid compounds that appear in the zygote during the prodromal period of sporulation. Both are derivatives of a phenol, gamma-L-glutaminyl-4-hydroxybenzene. When purified, these quinoids specifically inhibit mitochondrial respiratory enzymes and protein synthesis in the mushroom and have comparable effects with rat liver mitochondria and ribosomes, with intact bacteria, and with bacterial ribosomes and RNA polymerase in vitro. Five species of mouse ascites tumor cells showed prompt and marked inhibitions of nucleic acid and protein synthesis when millimolar concentrations of these quinoids were added to the tissue culture medium of the tumor cells. Only a small percentage of the cells was killed immediately, as judged by trypan blue uptake. When large numbers of exposed BP8 sarcoma and EL4 leukemic cells were reinjected intraperitoneally into histocompatible mice, the survival times of these animals were notably prolonged beyond those of animals injected with tumor cells that had not been exposed to these inhibitors. In a dose-dependent manner, increasing concentrations of inhibitors produced proportionate increments in survival time, while higher concentrations totally abolished tumor cell growth. The findings indicate that these simple quinoid compounds, which initiate the dormant state in spores, produce a cytostatic state in mammalian tumor cells and thus potentially have strong antitumor properties (Am J Pathol 78:33-48, 1975).
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PMID:Cytostatic, cytocidal and potential antitumor properties of a class of quinoid compounds, initiators of the dormant state in the spores of Agaricus bisporus. 80 42

The synthesis of total and ribosomal RNA using nucleoids of Escherichia coli as template was measured; of the total RNA synthesized by endogenous RNA polymerase which only completes chains, and added RNA polymerase which initiates new chains, 50-70 and 3-5%, repectively, was rRNA. Total RNA synthesis by added enzyme, however, was 10-20 times higher than endogenous RNA synthesis; thus rRNA was synthesized at the same rate by the endogenous and the added enzyme. We conclude that the percentage rRNA in vitro is no measure of the rate of rRNA synthesis. Furthermore, it follows that the added enzyme, like the endogenous one, is packed at the physical limit on the ribosomal cistrons. Consequently, initiation of ribosomal cistrons by added enzyme was at or near the maximal rate possible for this system in which the elongation rate is 10-20% of that in vitro. When RNA synthesis was assayed at various ratios of RNA polymerase to phenol-extracted DNA, the amount of rRNA made per DNA, which is a measure of the frequency of transcription of ribosomal cistrons, varied. The ratio of rRNA synthesis relative to total RNA synthesis also varied, but in a different way, again leading to the conclusion that this ratio, as determined in vitro, does not reflect the efficiency of transcription of the ribosomal cistrons.
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PMID:Ribosomal and non-ribosomal RNA synthesis in vitro. 109 71

The loosely bound chromatin proteins of Ehrlich ascites hyperdiploid cells have been prepared by extraction of chromatin with 0.35 M NaCl. Sodium dodecyl sulfate gel electrophoresis of the 0.35 M NaCl-soluble chromatin proteins reveals high heterogeneity with a molecular weight range of 10,000 to 170,000. The 0.35 M NaCl-soluble chromatin proteins contain many components similar to the more tightly bound non-histone chromatin proteins complex with the loosely bound chromatin proteins by gradient dialysis, the inhibitory effect of histones on transcription of DNA in vitro was reduced. The reconstituted complex manifested a level of template activity similar to that of native chromatin as measured in an Ehrlich ascites tumor RNA polymerase reaction. The loosely bound chromatin proteins contain RNA as well as phosphoproteins. Phenol extraction or DNA affinity chromatography of these proteins yielded fractions enhanced 25- to 30-fold in phosphorus which were capable of stimulating DNA-templated RNA synthesis in vitro. The stimulation of transcription from DNA was template-specific, effective only with a DNA template prepared from Ehrlich ascites tumor, but not from rat liver, calf thymus, or chicken erythrocytes. In addition, the stimulatory effect of the specific DNA-binding proteins appears to be RNA polymerase-specific, the stimulation being manifested with Ehrlich ascites tumor nucleoplasmic RNA polymerase and not with Micrococcus luteus RNA polymerase. Thus, the loosely bound chromosomal proteins from Ehrlich ascites tumor contain a fraction that specifically binds to Ehrlich ascites tumor DNA and exhibits a template- and RNA polymerase-specific stimulatory effect on transcription from DNA.
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PMID:Study of the loosely bound non-histone chromatin proteins. Stimulation of deoxyribonucleic acid-templated ribonucleic acid synthesis by a specific deoxyribonucleic acid-binding phosphoprotein fraction. 111 17

Site-directed mutagenesis was used to examine the catalytic importance of 2 histidine and 4 arginine residues in Escherichia coli periplasmic acid phosphatase (EcAP). The residues that were selected as targets for mutagenesis were those that were also conserved in a number of high molecular weight acid phosphatases from eukaryotic organisms, including human prostatic and lysosomal acid phosphatases. Both wild type EcAP and mutant proteins were overproduced in E. coli using an expression system based on the T7 RNA polymerase promoter, and the proteins were purified to homogeneity. Examination of the purified mutant proteins by circular dichroism and proton NMR spectroscopy revealed no significant conformational changes. The replacement of Arg16 and His17 residues that were localized in a conserved N-terminal RHGXRXP motif resulted in the complete elimination of EcAP enzymatic activity. Critical roles for Arg20, Arg92, and His303 were also established because the corresponding mutant proteins exhibited residual activities that were not higher than 0.4% of that of wild type enzyme. In contrast, the replacement of Arg63 did not cause a significant alteration of the kinetic parameters. The results are in agreement with a previously postulated distant relationship between acid phosphatases, phosphoglycerate mutases, and fructose-2,6-bisphosphatase. These and earlier results are also consistent with the conclusion that 2 histidine residues participate in the catalytic mechanism of acid phosphatases, with His17 playing the role of a nucleophilic acceptor of the phospho group, whereas His303 may act as a proton donor to the alcohol or phenol.
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PMID:Overexpression, site-directed mutagenesis, and mechanism of Escherichia coli acid phosphatase. 142 31

It is generally assumed that the machinery that transcribes genes is composed entirely of polypeptides. However, in vitro transcription by silkworm RNA polymerase III requires a transcription factor that is not a polypeptide. This component, TFIIIR, is distinct from the previously identified transcription components: RNA polymerase III, and the accessory factors TFIIIA, TFIIIB, TFIIIC, and TFIIID. The newly discovered TFIIIR is a macromolecule that appears to be composed of RNA. It is resistant to heat, detergent, phenol, protease, and deoxyribonuclease, but it is sensitive to alkali and ribonuclease.
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PMID:A class III transcription factor composed of RNA. 170 25

Influence of water solutions of chemically pure adaptogen--synthetic analog of Rhodiola Rosea extract phenol composition (SAR) on functional activity of hemopoietic and tumor cells of mice with Ehrlich ascite cancer was studied in vitro. The periodical character of SAR effects was shown to be different for both types of cells, and at 1 x 10(-2) and 1 x 10(-26) M concentrations simultaneous stimulation of blood marrow cells colony-forming activity and inhibition of the latter in tumor elements was revealed. Essential changes of reactions of both cell types after adding the DNA-dependent RNA polymerase blocker Actinomycin D permit to suggest SAR effects to be connected with drug influence on the membrane RNA of the target cells.
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PMID:[Mechanism of differential effect of low dose adaptogens on the functional activity of normal and transformed cellular elements in vitro]. 179 47

Isolated rat liver nuclei were incubated under conditions when RNA polymerase I or RNA polymerase II was preferentially active. It was shown that [gamma-32P] ATP and [gamma-32P] GTP were incorporated into phenol extractable, TCA-precipitable material. RNase, actinomycin D, heparin and, in the case of RNA-polymerase II, alpha-amanitine inhibited precursor incorporation. These data are interpreted as evidence in favour of the initiation of RNA synthesis in isolated rat liver nuclei.
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PMID:[Initiation of RNA synthesis in isolated rat liver nuclei]. 258 May 66


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