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

---

Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two major cyclic nucleotide-independent protein kinases, NI and NII, have been identified in Morris hepatoma 3924A and rat liver. When expressed per unit DNA, the activities of protein kinase NI and NII were 1.3 and 12 times greater, respectively, in the hepatoma than in liver. Protein kinase NII, but not NI, was capable of phosphorylating and activating the DNA-dependent RNA polymerases I and II. Phosphorylation of RNA polymerase I was accompanied by an increase in average size of the RNA synthesized in vitro, whereas phosphorylation of RNA polymerase II was concomitant with an elevation in the number of RNA chains initiated. RNA polymerase I polypeptides of Mr 120,000, 65,000 and 25,000 were phosphorylated by protein kinase NII; RNA polymerase II polypeptides of Mr 214,000, 140,000 and 21,000 were modified by this kinase. In contrast to the purified hepatoma enzyme, RNA polymerase I activity in nuclear lysates was not affected by addition of protein kinase NII. In vitro phosphorylation of the tumor lysate followed by immunoprecipitation of RNA polymerase I polypeptides indicated little or no phosphate transfer to the 65,000 Mr polypeptide of the enzyme. These data suggested that the tumor enzyme, particularly the 65,000 Mr polypeptide, was highly phosphorylated in vivo, but becomes dephosphorylated during purification. Unlike the tumor enzyme, RNA polymerase I in the liver lysate responded to protein kinase addition; phosphorylation of the liver polymerase I polypeptides of Mr 120,000, 65,000 and 25,000 was observed. These observations indicate that the liver enzyme is not completely phosphorylated (activated) in vivo and that the relatively rapid rate of ribosomal RNA synthesis in the rapidly growing hepatoma may result, at least in part, from a polymerase I which is maximally phosphorylated.
...
PMID:RNA polymerase I in hepatoma 3924A: mechanism of enhanced activity relative to liver. 654 82

Relative to resting liver, Morris hepatomas with different growth rates (3924A, 5123D, 7800, and 7777) all had higher (two to eightfold) levels (activity/gm tissue) of RNA polymerase I. Only the most rapidly growing tumor (hepatoma 3924A) showed a substantial increase (fivefold) in RNA polymerase III activity. RNA polymerase II activity/gm tissue in the hepatomas was similar to that in resting liver. The elevation in the hepatoma RNA polymerase I activity resulted from both an increase in the number of transcriptionally active enzyme molecules and an increase in the specific activity of the enzyme as a result of phosphorylation. Phosphorylation of RNA polymerase I from Morris hepatoma 3924A could be catalyzed either by an endogenous protein kinase or by a highly purified preparation of NII protein kinase from the same tumor. Three out of eight polypeptides (Mr 120,000, 65,000, and 25,000) or RNA polymerase I were phosphorylated. Phosphorylation resulted in enhanced RNA synthesis at the level of chain elongation. Another nuclear protein kinase, NI, had no significant effect on RNA polymerase I. The activity and/or amount of the NII protein kinase was significantly reduced in resting liver, which correlated with decreased specific activity of the liver RNA polymerase I. Anti-RNA polymerase I antibodies were found in the sera of patients with rheumatic autoimmune diseases such as systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), and rheumatoid arthritis (RA). Sera from these patients were capable of specifically inhibiting RNA polymerase I activity in vitro. Antibodies were produced predominantly against three of the polypeptides--S3 (Mr 65,000), S4 (Mr 42,000), and S5 (Mr 25,000) of RNA polymerase I. The spectrum and proportion of the antibodies against these three subunits differ with each patient and with the type of the autoimmune disease. These observations indicate that (1) the NII kinase can regulate RNA polymerase I activity, (2) protein kinase NII is associated with the polymerase I enzyme complex, and (3) certain polypeptides of this enzyme complex may be the target antigens in rheumatic autoimmune disease.
...
PMID:Regulation of RNA polymerase I by phosphorylation and production of anti-RNA polymerase I antibodies in rheumatic autoimmune diseases. 660 44

By serial transplantation of CS 1, a subline of Shionogi carcinoma SC 115, to female mice, another subline was obtained and designated CS2. The subline showed a complete loss of androgen dependency on the growth of the tumor. When male mice bearing the tumor were castrated and treated with testosterone, the activity of RNA polymerase I in isolated nuclei from the tumor hardly varied during the period of the experiments (36 h), while the activity of RNA polymerase II exhibited a transient increase (about 40%) at 6 h after the testosterone injection. The results, together with the previous ones showing 80% and 40% increases in RNA polymerase I activity at 24 h after testosterone administration in the case of SC 115 (androgen-dependent tumor) and CS 1 (less androgen-dependent tumor), respectively, indicate that the stimulation of RNA polymerase I activity by androgen in the tumor tissues is closely related to the androgen dependency on the growth of the tumors.
...
PMID:In vitro effect of androgen on RNA synthesis in nuclei from androgen-independent subline of Shionogi carcinoma (CS 2). 667 65

6-Mercaptopurine was found to inhibit the growth of cultured human lymphoma P3HR-1 cells and the incorporation of [3H]-uridine into trichloroacetic acid-precipitable materials of the cells. One of the derivatives of 6-mercaptopurine, 6-mercaptopurine ribonucleoside triphosphate (6-thio-ITP), was found to inhibit in vitro RNA synthesis (both engaged and free enzyme activities) of the isolated nuclei from P3HR-1 cells. The alpha-amanitin-resistant RNA polymerase (polymerase I) and alpha-amanitin-sensitive RNA polymerase (polymerase II) of the cells were isolated and partially purified by either diethylaminoethyl cellulose or diethylaminoethyl Sephadex column chromatography, followed by DNA-cellulose affinity chromatography. It was found that these partially purified enzymes were also sensitive to 6-thio-ITP inhibition. Kinetic studies showed that the inhibition of RNA polymerase activities by 6-thio-ITP could be reversed by increasing concentrations of guanosine 5'-triphosphate in the reaction mixture, indicating that 6-thio-ITP may act as a competitive inhibitor of the enzymes by competing with guanosine 5'-triphosphate for its enzyme-binding site. These data suggest that inhibition of RNA transcription by 6-thio-ITP may be considered as one of the mechanisms of the cytotoxic action of 6-mercaptopurine in human tumor cells.
...
PMID:Inhibition of human lymphoma DNA-dependent RNA polymerase activity by 6-mercaptopurine ribonucleoside triphosphate. 668 25

A procedure was developed for large scale purification of RNA polymerase II from Ehrlich ascites tumor cells. About 2 mg of purified enzyme was obtained from 800 g of wet cells. Ten subunits were identified which behaved corresponding to the enzyme activity both on DEAE-Sephadex chromatography and on glycerol density gradient centrifugation. Analysis of tryptic peptides of each subunit showed that these subunits were independent proteins and not structurally related to each other.
...
PMID:Identification of subunits of RNA polymerase II from Ehrlich ascites tumor cells. 668 13

The DNA binding subunits of RNA polymerase II from Ehrlich ascites tumor cells were investigated in the following three ways. (1) RNA polymerase II was dissociated in urea and the binding of the dissociated subunits to DNA was investigated. (2) The RNA polymerase II: DNA complex was dissociated progressively with various concentrations of urea, and the subunits firmly attached to DNA were investigated. (3) RNA polymerase II was dissociated into subunits in a SDS-polyacrylamide gel containing urea and blotted onto a nitrocellulose filter. The filter was then incubated with 32P-nick-translated DNA to identify the DNA binding subunits. These procedures all showed that the largest subunit a of RNA polymerase II had strong affinity to DNA. It was found that a portion of subunits b and c could be recovered in DNA fraction when analyzed by procedures (1) and (2), but no significant DNA binding activity was detected when analyzed by procedure (3), suggesting that these subunits have either a much weaker affinity toward DNA compared to a or have affinity to a itself.
...
PMID:Identification of the DNA binding subunit of RNA polymerase II from Ehrlich ascites tumor cells. 668 76

Variant double-stranded RNAs are often associated with the genome of transmission-defective isolates of wound tumor virus. These RNAs are replicated and packaged into virus particles in systemically infected plants and are transcribed in vitro by the virion-associated transcriptase. Direct physical evidence that the variant RNAs are remnants of particular WTV genome segments was provided by molecular hybridization studies. Subsequently, ribonuclease T1 digestion products of 3'-end-labeled genome and remnant RNAs were analyzed by one- and two-dimensional electrophoretic techniques. One-dimensional partial and complete digestion patterns were indistinguishable, indicating that the guanosine positions relative to the 3' terminus of the corresponding strands of a particular genome segment and its remnant RNA are the same for at least 40 nucleotides from each end. Fingerprints of the 3' terminal ribonuclease T1-resistant fragments were identical, showing that the nucleotide composition of the 3' terminal ends of the corresponding strands of a particular genome segment and its remnant RNA are also identical. These results indicate that variant RNAs associated with transmission-defective WTV isolates are formed by deletion of an internal portion (as much as 85%) of genomic RNA segments yielding terminally conserved genomic remnants that are functional with respect to transcription, replication, and packaging.
...
PMID:Variant dsRNAs associated with transmission-defective isolates of wound tumor virus represent terminally conserved remnants of genome segments. 671 Aug 65

When adenovirus type 5-infected HeLa cells were exposed to the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate, short pulse-labeling with [3H]uridine in vivo and [3H]UTP incorporation by isolated nuclei in vitro were both consistent with a decreased latent period before initiation by RNA polymerase at early viral promoters. Acceleration was not dependent upon concurrent protein synthesis and could not be attributed to rapid entry of virus into the cell nucleus. 12-O-tetradecanoyl-phorbol-13-acetate suppressed the transcription-delay phenotype of the E1a mutant, hr1, without restoring its ability to replicate.
...
PMID:Accelerated onset of viral transcription in adenovirus-infected HeLa cells treated with the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate. 671 33

Three proteins stimulating RNA polymerase II were purified from Ehrlich ascites tumor cells. Antibody was raised against one of these proteins. Immunofluorescent study revealed that these proteins ubiquitously exist in the nucleoplasm of various eukaryotic cells. This antibody specifically inhibited alpha-amanitin-sensitive RNA synthesis in isolated nuclei of Ehrlich ascites tumor cells and accurate transcription in HeLa cell lysate, indicating that these proteins are essential components of eukaryotic transcription. Two proteins were shown to have the same primary structure except that one of them is phosphorylated.
...
PMID:Stimulatory proteins of RNA polymerase II from Ehrlich ascites tumor cells. 675 Mar 56

To observe the effect of sex hormones on RNA synthesis of androgen-dependent tumors, mice of DD/S strain bearing androgen-dependent mouse mammary tumor (SC 115) were treated with the hormones, and RNA polymerase activities in isolated nuclei of the tumor were measured. The activity of RNA polymerase I in SC 115 was diminished to approximately 60% of the control level by castration, and it was restored to the precastrated level 12 hr after treatment with 0.2 mg of testosterone. While the activity of RNA polymerase II in the tumor was scarcely influenced by castration, it reached 150% of the castrated level 24 hr after administration of testosterone. In CS 1, a subline of SC 115 with partial loss of androgen dependency on growth, castration and testosterone treatment caused similar but less prominent effects on the activities of RNA polymerase. Administration of estradiol-17 beta to castrated animals also increased the activity of RNA polymerase I, but to a lesser degree than testosterone, in both SC 115 and CS 1. However, only SC 115 demonstrated an increase in RNA polymerase II after estrogen treatment.
...
PMID:Effect of sex hormones on RNA synthesis of androgen-dependent mouse mammary tumor (Shionogi carcinoma). 688 72


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

---