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 literature indicates that some mechanism other than the interferon or host-mediated immune enhancement might also be responsible for an antitumor effect of polyinosinate-polycytidylate [poly(I)-poly(C)]. We have examined the effect of this drug on the synthesis of ribosomes and other macromolecules in a rat tumor, the Novikoff ascites hepatoma. The nucleolus was one of the primary targets affected by the administration of poly(I)-poly(C) in vivo. A progressive decline of the activity of nucleolar ribosomal RNA methylases began within 2 hr, followed by a decline of the nucleolar RNA content. The activity of nucleolar RNA polymerase was inhibited only at later time intervals. Labeling of tumor macromolecules in vivo revealed that the methylation of ribosomal RNA and the production of ribosomes, particularly in the small subunits, were immediately and progressively affected, followed by inhibition of the synthesis of DNA, RNA, and protein at later times. In addition, poly(I)-poly(C) also induced disaggregation of polyribosomes and restricted the movements of nuclear RNA to cytoplasm and of cytoplasmic protein to nucleus. These in vivo effects of poly(I)-poly(C) on tumor cells was observed neither on the host livers nor on livers of normal rats. Studies on isolated nucleoli showed that the in vitro addition of polyinosinate and several other compounds actively inhibited tumor ribosomal RNA methylases but were devoid of inhibitory effect against liver ribosomal RNA methylases; these results augment other studies in the literature in suggesting a selective effect of the polyinosinate moiety on tumor cells. We conclude from this study that initial impairment of the methylation of ribosomal precursor RNA, following exposure of tumor cells to poly(I)-poly(C), is responsible for the destruction of ribosomes, preferentially the small subunits, during the maturation processes. Failure to provide new ribosomes thus triggers the events limiting the growth of tumor cells.
Cancer Res 1975 Sep
PMID:Preferential inhibition by homopolyribonucleotides of the methylation of ribosomal ribonucleic acid and disruption of the production of ribosomes in a rat tumor. 16 54

Upon infection of Chinese hamster ovary cells (CHO), vesicular stomatitis (VSV) virus synthesizes two membrane proteins (the VSV glycoprotein and the VSV matrix or membrane (M) protein) and three nonmembrane proteins (the VSV nucleocapsid, the viral transcriptase, and an NS protein). We have used the VSV-infected cell as a model system for the study of the site of synthesis of these membrane and nonmembrane proteins. We have isolated VSV mRNA from free polyribosomes, membrane-bound polyribosomes, and the postribosomal supernatant, and identified the individual species of VSV mRNA present in each fraction. The mRNA which encodes the VSV glycoprotein is found exclusively on membrane-bound polyribosomes, while the mRNAs which encode the VSV, M, N, and NS proteins are found in free polyribosomes, in the membrane fraction of the cell, and in the postribosomal supernatant. Our results suggest that the VSV glycoprotein is synthesized exclusively on membrane polyribosomes, while at least some of the M, N, and NS proteins are made on free polyribosomes.
J Biol Chem 1975 Sep 10
PMID:Site of synthesis of membrane and nonmembrane proteins of vesicular stomatitis virus. 16 63

We have investigated the manner by which progesterone receptors act to induce initiation of RNA synthesis in a cell-free system derived from chick oviduct. A method utilizing rifampicin enabled us to measure the formation of binary initiation complexes between RNA polymerase and chick oviduct chromatin (Tsai, M.-J., Schwartz, R.J., Tsai S.Y., and O'Malley, B.W. (1975) J.Biol. Chem. 250, 5165-5174) and allowed for the quantitative assessment of RNA chain initiation sites, RNA chain propagation rates, and RNA chain size under conditions which prevent secondary chain reinitiations. We have measured the available initiation sites for transcription in oviduct chromatin prepared from chicks withdrawn from all hormone and then restimulated with a secondary injection of progesterone. Within 1/2 hour after administration of progesterone, the number of initiation sites increased from 8,700 sites/pg of chromatin DNA for the control to 15,500 sites. After 1 hour, the concentration of RNA polymerase needed to saturate chromatin binding sites was increased 60% in comparison to control values, while the number of initiation sites increased 160%. This rapid increment in transcriptional activity preceded temporally the induction of synthesis of ovalbumin mRNA. To test directly the effect of progesterone receptor on transcription, in vitro, a reconstituted cell-free system was employed which contained purified cytoplasmic progesterone-receptor complexes, Escherichia coli RNA polymerase, and chromatin prepared from hormonally withdrawn chick oviducts. Purified progesterone-receptor complex stimulated transcription of oviduct chromatin in vitro by promoting an increase of 3,000 to 5,000 additional sites for RNA chain initiation. These data showed that progesterone receptor can directly increase the number of RNA polymerase binding and initiation sites in the chromatin template in the absence of a detectable change in either the rate of RNA chain propagation or the size of the RNA product. The kinetics of progesterone-receptor stimulation of RNA synthesis in chromatin revealed a t1/2 of 15 min for this effect to occur. This value was identical with the optimal time required for binding of receptor to chromatin. The concentration of receptor required for half-maximal stimulation of RNA chain initiation was approximately 5 x 10(-9) M. This value agreed closely with our previously reported estimates of the affinity (Kd approximately 5 x 10(-9)M) of the progesterone-receptor complex for oviduct chromatin. The stimulatory effect of purified progesterone receptor appeared to be relatively specific for oviduct chromatin in comparison to nontarget tissue chromatins or chick DNA. The data presented here show that steroid hormone-receptor complex can directly regulate gene transcription in vitro in a manner which mimics the events observed in vivo in target cells.
J Biol Chem 1976 Sep 10
PMID:Progesterone-binding components of chick oviduct. In vitro effects of purified hormone-receptor complexes on the initiation of RNA synthesis in chromatin. 18 91

Phosphorylation of rat liver RNA polymerase I occurred when intact rat liver nuclei were incubated with [gamma32P]ATP and N6,O2' dibutyryl cyclic 3':5'-AMP. In addition, partially purified RNA polymerase I could be phosphorylated in vitro by an endogenous protein kinase. Phosphorylation by either method was followed by extensive purification of the enzyme. This revealed that 32P remained bound to the enzyme throughout purification. Analysis of the homogeneous labeled protein by polyacrylamide gel electrophoresis under nondenaturing conditions followed by autoradiography revealed that only one of the two forms of RNA polymerase I in rat liver nuclei was phosphorylated. RNA polymerase II was not phosphorylated in intact nuclei. Polyacrylamide gel electrophoresis of the phosphorylated RNA polymerase I in the presence of 0.1% sodium dodecyl sulfate followed by autoradiography demonstrated that the 32P was located primarily on enzyme subunits SA1, SA3, and SA5-SA6. High voltage paper electrophoresis of a partial acid hydrolysate of phosphorylated RNA polymerase I revealed that both serine and threonine residues were phosphroylated. N6,O2'-Dibutyryl cyclic 3':5'-AMP stimulated endogenous RNA polymerase I activity and endogenous nuclear protein phosphorylation in intact nuclei. These results suggest that phosphorylation of RNA polymerase I by nuclear protein kinases may play a role in the control of transcription in mammalian cells.
J Biol Chem 1976 Sep 10
PMID:Phosphorylation of rat liver ribonucleic acid polymerase I by nuclear protein kinases. 18 96

A rat liver nuclear envelope fraction isolated essentially by the technique of Monneron et al. (J. Cell Biol. 55, 104-125 (1972) is characterized by high levels of glucose-6-phosphatase and 5'-nucleotidase. A broadly specific nucleoside triphosphatase activity is present. Cytochromes b5 and P-450 as well as NADPH- and NADH-cytochrome c reductase activities are present but at lower levels than found in microsomes. Cytochrome c oxidase activity is low. RNA polymerase activity is absent from the nuclear envelope fraction. Cytochemistry shows that glucose-6-phosphatase activity is strong and restricted to the nuclear envelope of nuclei. 5'-Nucleotidase shows weak reaction deposit in whole nuclei but in contrast gives clear reaction deposit in isolated nuclear envelopes. Cytochemical reaction deposit due to nucleoside triphosphatase activity is not restricted to the nuclear envelope but is found to a larger extent within the nucleus.
Biochim Biophys Acta 1976 Sep 21
PMID:An enzymic analysis of a nuclear envelope fraction. 18 34

The hybridization properties of the herpes simplex virus type 1 (HSV) genome have been analysed. The DNA has a kinetic complexity of 1 X 10(-8). E. cole RNA polymerase was found to initiate synthesis at about 70 sites on the HSV DNA. The in vitro RNA product from this reaction was complementary to about 80% of the HSV genome. The RNA-DNA hybridization rate constant (Kh) was determined using conditions of both RNA excess and DNA excess. Using this rate constant one can analyse the content of HSV sequences in any RNA population.
J Gen Virol 1976 Sep
PMID:Annealing and hybridization properties of herpes simplex virus type 1 DNA. 18 38

The RNA polymerase in cells infected with three group I mutants of vesicular stomatitis virus has been examined. Mouse L cells were incubated at the permissive temperature (30 degrees C) for a few hours after infection to allow the development of secondary transcription. The temperature dependence of the secondary transcription system was determined from the incorporation of labelled uridine, in the presence of cycloheximide, at 30 and at 38 degrees C, the later temperature being non-permissive for viral replication. In cells infected with mutants W14, W28, and G11 at a low multiplicity (20 PFU/cells) secondary transcriptase activity was markedly temperature-sensitive after 3 and 5 h of infection at 30 degrees C. At a high multiplicity of infection (1000 PFU/cell) cells infected with W28 showed considerable RNA synthesis at 38 degrees C after 3 h at 30 degrees C. RNA synthesis was also observed in W28-infected cells in which protein synthesis was allowed to continue after the shift from 30 to 38 degrees C. In the latter two cases the RNA synthesized contained 12-18S species but little or no 30S mRNA.
Can J Microbiol 1976 Sep
PMID:Temperature-sensitive mutants of vesicular stomatitis virus: viral RNA synthesis in cells infected with mutants belonging to complementation group I. 18 5

Two-dimensional polyacrylamide gel electrophoresis shows that in nuclei of Novikoff hepatoma ascites cells there are approximately 75 proteins in the chromatin fraction soluble in 3 M NaCl:7 M urea. Dialysis of this fraction to an ionic strength of 0.15 produces a soluble fraction and a precipitate. The proteins in the soluble fraction have been reported to be active in gene control. Antibodies to the soluble fraction distribute diffusely throughout the nucleus, and antibodies to the precipitate localized primarily in the nucleolus and the nuclear ribonucleoprotein network. The nucleolar proteins differ from the extranucleolar proteins in antigenicity and labeling patterns. The development of methods for isolation, purification, and identification of nuclear proteins provided the opportunity for analysis of chromatin antigens in tumor cells. Utilizing two-dimensional preparative polyacrylamide gel techniques as well as conventional procedures, several nuclear proteins have been isolated in electrophoretically homogeneous states including protein A-24, a histone-like nonhistone protein; C-14, a protein that stimulates nucleolar RNA polymerase; and a chromatin antigen soluble in 3 M NaCl:7 M urea that remains soluble after dialysis to 0.15 M NaCl to precipitate the histones and the DNA. This antigen has been found in the chromatin of both the Novikoff hepatoma and the Walker 256 carcinosarcoma but not in the chromatin of either normal or regenerating liver. It is a nonhistone nuclear protein as indicated by its amino acid analysis in which the ratio of the number of acidic to basic amino acids is approximately 1.4. Further studies are in progress on the function and structure of this chromatin protein. As an approach to analysis of relative rates of synthesis of this antigen and otherproteins, the products of translation of messenger RNA of Novikoff hepatoma and normal liver are being analyzed by autoradiography of two-dimensional electrophoretic gels.
Cancer Res 1976 Sep
PMID:Antigenically active nonhistone chromatin proteins in cancer cells. 18 49

Progesterone causes in goblet cells of oviducts of estrogen hormone-stimulated immature quails selectively gene activation without affecting DNA synthesis. This biological model has been used to study the influence of poly ADP-ribosylation during the processes of DNA transcription. Administration of progesterone in vivo causes an increase of the activity of RNA polymerase I and II in isolated nuclei. This increase is accompanied by a marked decrease of the specific activity of poly (ADP-Rib) polymerase. After in vitro ADP-ribosylation of nuclear proteins the template capacity of chromatin for ""exogenous'' RNA synthesis (with E. coli DNA-dependent RNA polymerases) as well as for ""endogenous'' RNA synthesis with DNA dependent RNA polymerases II is not affected, whereas the data presented seem to indicate that the capacity for RNA synthesis mediated by ""endogenous'' DNA-dependent RNA polymerase I might be inhibited after ADP-ribosylation. Evidence is presented to show that a considerable amount of poly (ADP-Rib), synthesized by poly (ADP-Rib) polymerase in isolated nuclei, is linked with RNA polymerase I. The rate of synthesis of poly (ADP-Rib) is dependent on the incubation temperature (optimum at 25 degrees C) and it can be inhibited by the specific inhibitors of poly (ADP-Rib) polymerase nicotineamide, thymidine and formycin B. Poly (ADP-Rib) is probably associated with RNA polymerase I through a covalent linkage. ADP-ribosylated RNA polymerase I has been purified 550 fold with respect to the nuclear extract corresponding to a 4,000 fold purification from the whole cell homogenate. The ratio between poly (ADP-Rib), formed during preincubation of nuclei with NAD, and RNA polymerase I remains almost constant during the purification procedures. The extent of ADP-ribosylation of RNA polymerase I decreases during gene expression. Thus we conclude that poly ADP-ribosylation of this enzyme is one of the regulatory mechanisms by which specificity of DNA transcription is achieved.
Mol Cell Biochem 1976 Sep 30
PMID:Poly ADP-ribosylation of DNA-dependent RNA polymerase I from quail oviduct. Dependence on progesterone stimulation. 18 9

A previous report from this laboratory showed that purified DNAs are transcribed after injection into the nucleus of Xenopus laevis oocytes (Mertz and Gurdon, 1977). Here we demonstrate that at least some of the RNA synthesized is translated within these injected cells to produce the correct protein products. Injection of Simian Virus 40 DNA into oocytes induces the synthesis of at least two proteins not normally synthesized in these cells. Using two-dimensional polyacrylamide gel electrophoresis and well characterized deletion mutants of SV40 that produce proteins of smaller size, we show that these two proteins are, indeed, the virus-coded proteins VP1 and VP3. Synthesis of VP1 and VP3 is inhibited by alpha-amanitin and, therefore, presumably mediated by a type II RNA polymerase. We also present evidence indicating that a histone-like protein is induced after the injection of a cloned plasmid DNA that codes for the Drosophila melanogaster histone proteins. This in vivo coupled transcription-translation system should be useful for identifying and mapping proteins coded by cloned eucaryotic DNAs.
Cell 1977 Sep
PMID:Coupled transcription-translation of DNA injected into Xenopus oocytes. 19 38


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