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)

Human endothelial cells isolated from hepatic sinusoids were infected in vitro with human immunodeficiency virus type 1 (HIV-1). An early sign of infection occurring in the culture was the formation of multinucleated cells. By double-labeling immunofluorescence, 5-15% of the cells recognized as endothelial cells owing to the presence of von Willebrand factor were found to contain HIV p24 and gp120 antigens after 2 weeks. Reverse transcriptase activity was released into the medium, and different steps in the process of viral budding were observed by electron microscopy. The virus produced by the endothelial cells was found to be infectious for CEM cells, a human T-cell line. CD4 molecules are present at the surface of the endothelial cells, as demonstrated by immunogold-silver staining and backscattered electron imaging. Treatment with an anti-CD4 antibody abolished productive infection of the sinusoidal endothelial cells. The possibility that endothelial cells of the liver sinusoid are infected in vivo with HIV remains to be clearly shown.
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PMID:Primary cultures of endothelial cells from the human liver sinusoid are permissive for human immunodeficiency virus type 1. 137 78

We have studied the transcription of highly repeated satellite-like Bsp elements containing the potential promoter boxes for RNA polymerase III in the genomes of adult silver and arctic foxes. The Bsp repeat transcripts were abundant enough to be detected by Northern blot and semiquantitative dot blot hybridizations, and the majority were found in the nuclear RNA fraction from arctic fox kidneys. Weak hybridization signals were revealed with the cytoplasmic RNA preparation from silver fox kidneys and with the nuclear RNA fraction from arctic fox liver, and their intensity was intermediate with the total RNA from arctic fox brain. Taken together, the data suggest possible genomic interspersion of some Bsp repeats in these two representatives of Canidae. The observed species-and tissue-specificity of the transcription of Bsp repeats suggests that they may potentially accomplish regulatory functions in the fox genomes.
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PMID:Species- and tissue-specific transcription of complex, highly repeated satellite-like Bsp elements in the fox genome. 137 64

We report on the discovery and isolation of DNA- and RNA-containing macromolecular nuclear complexes whose purified major DNA possessed electrophoretic mobilities of approximately 90 and approximately 25 kbp. The deoxyribonucleoprotein-ribonucleoprotein complexes contain RNA and DNA polymerase and primase activities and were isolated from nuclei of murine RAW117 large-cell lymphoma cells by restriction digestion with Msp-I, gentle extraction with solutions containing MgCl2, but without chelating agents, and low ionic strength gel electrophoresis. Two-dimensional (isoelectric focusing/M(r)) gel electrophoresis and silver staining of the proteins of the complexes after treatment with DNase I indicated the presence of approximately 30 protein components. In vitro DNA and RNA polymerase/primase assays showed that the DNP/RNP complexes had very high enzyme specific activities. Using the DNP/RNP complexes a discrete DNA polymerase alpha product of approximately 85 kbp was synthesized that was not synthesized in the presence of the DNA polymerase alpha inhibitor aphidicolin. RNA polymerase assays in the presence of excess alpha-amanitin indicated that the complexes possessed significant RNA polymerase I activity. Preparing the complexes at various times after the release of cells from a double thymidine block showed the complexes as well as the complex-associated enzyme activities to be cell-cycle dependent. The DNA and RNA polymerase-related activities were highest in late S phase, 7 and 9 h, respectively, after release from the double thymidine block. The complexes synthesized a specific in vitro DNA polymerase product using endogenous substrate and nucleotide precursors.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Nucleoprotein complexes released from lymphoma nuclei that contain the abl oncogene and RNA and DNA polymerase and RNA primase activities. 142 73

A simple and rapid method to copurify RNA polymerase I and the glucocorticoid-regulated transcription factor, TFIC, is described. This protocol results in 1262-fold purification and 15% total recovery of the enzyme and factors needed to support faithful transcription in vitro from cloned mouse rRNA gene (rDNA). Using this method, proteins involved in rDNA transcription were purified from exponentially growing lymphosarcoma P1798 cells as well as cells treated with 0.1 microM dexamethasone. A combination of transcription and reconstitution assays using G-free cassette-containing constructs and polyacrylamide gel electrophoretic analysis upon silver staining were used to detect TFIC activity as well as the characteristic TFIC polypeptides in control and dexamethasone-treated cell extracts. Treatment of P1798 cells with 0.1 microM dexamethasone for 24 h results in an over 95% reduction of TFIC activity, but no significant differences in the amount of TFIC polypeptides in the final product purified from control and glucocorticoid-treated cells could be detected. Our data indicate that glucocorticoid regulation of transcription of rDNA is mediated via post-translational modulation of the activity of TFIC.
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PMID:Copurification of RNA polymerase I and the glucocorticoid-regulated transcription factor IC. 145 55

Yeast nuclear RNA polymerases are multisubunit enzymes that contain in common some small subunits. We show that the smallest, a 10-kDa component of three enzymes (A10, B10, and C10), is heterogeneous. In each case, it can be resolved into two distinct polypeptides (alpha and beta) by reverse-phase chromatography. A10 alpha, B10 alpha, and C10 alpha were indistinguishable on the basis of their electrophoretic and chromatographic behaviors, characteristic silver staining, and tryptic peptide analysis. All three polypeptides are blocked at their amino termini. By the same criteria, A10 beta, B10 beta, and C10 beta were also indistinguishable. The amino-terminal sequence of A10 beta and C10 beta corresponded to that of subunit B10 recently cloned by Woychik and Young (Woychik, N. A., and Young, R. A. (1990) J. Biol. Chem. 265, 17816-17819). Thus, the three forms of RNA polymerase share two additional and distinct polypeptides, ABC10 alpha and ABC10 beta, that therefore can be considered bona fide subunits of these enzymes. Interestingly, these two subunits bind zinc.
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PMID:Two additional common subunits, ABC10 alpha and ABC10 beta, are shared by yeast RNA polymerases. 174 81

Nucleolar organizer regions (NOR's) are loops of deoxyribonucleic acid (DNA) which transcribe to ribosomal ribonucleic acid (RNA) by RNA polymerase I. They possess vital significance in the ultimate synthesis of cellular proteins. A silver colloid staining technique for demonstration of NOR-associated proteins (Ag-NOR's) was applied to paraffin-embedded sections from 128 varied brain tumors and to chromosomal preparations from cultured brain-tumor cells. There was a statistically significant difference in the mean number of Ag-NOR's per nucleus between low-grade tumors (1.98/nucleus) and high-grade tumors (2.95/nucleus). It is suggested that the mean number of Ag-NOR's may represent the proliferative potential of brain tumors. Furthermore, high-grade tumors usually showed relatively large Ag-NOR's in a scattered distribution. In chromosomal preparations, the cultured cells displayed five to 12 Ag-NOR's on acrocentric chromosomes. Five of eight cell lines examined demonstrated ectopic Ag-NOR's. This simple staining technique can be easily applied to routinely processed paraffin-embedded sections and will become a useful tool for quick estimation of the proliferative potential of human brain tumors.
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PMID:Nucleolar organizer regions in various human brain tumors. 203 60

Specific transcription complexes were formed with yeast RNA polymerase I using a cognate oligoribotri-nucleotide primer (GCG) to initiate transcription on short synthetic single-stranded DNA templates. The templates were designed to limit the incorporation of a photoprobe, 4-thiouridine triphosphate, to a single unique position at the 3' terminus of the product RNA (position 12, 13, 14, or 15). The resulting transcription complexes were photolyzed to cross-link the bound transcript (radiolabeled with [alpha-32P]CTP) to the protein with the probe located at the catalytic site. Separation of the protein subunit components by 5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and analysis by autoradiography and silver staining revealed that the two largest subunits (A190 and A135) were radiolabeled. The ratio of subunit labeling (A190/A135) decreased as the RNA transcript increased from 12 to 15 nucleotides in length. This decrease in ratio resulted from a progressive reduction of A190 subunit labeling while the A135 subunit derivatization remained essentially constant. It was also observed that the DNA template was radiolabeled.
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PMID:Yeast RNA polymerase I. Derivatization of the 190 and 135 subunits by 4-thiouridine monophosphate positioned uniquely at the 3' terminus of an enzyme-bound 32P-containing transcript initiated by a triribonucleotide primer on synthetic single-stranded DNA. 215 57

Mitochondrial RNA-processing endoribonuclease (RNAase MRP) has the capacity to cleave mitochondrial RNA complementary to the light strand of the displacement loop at a unique site. The enzyme is a ribonucleoprotein whose RNA component is a nuclear gene product. The 5' flanking region of the primary transcript has control elements characteristic of RNA polymerase II transcription, and the coding region has features of RNA polymerase III transcription signals. The RNA associated with RNAase MRP is the first known RNA encoded by a single-copy gene in the nucleus and believed to be imported into mitochondria. The gene (RMRP) for this RNA component of RNAase MRP was assigned to human chromosome 9 and mouse chromosome 4 by Southern blot analyses of 11 human X rodent hybrids and 11 mouse X rodent hybrids with probe pHM1.0 and probe pSP270, respectively. In situ hybridization of probe pHSTU300 to normal human chromosomes revealed 29 of 100 cells with label on 9p and 9.6% of 302 silver grains located at 9p21--p12.
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PMID:The gene for the RNA component of the mitochondrial RNA-processing endoribonuclease is located on human chromosome 9p and on mouse chromosome 4. 232 93

Cloned human rRNA gene fragments that included the promoter region were introduced into Chinese hamster dihydrofolate reductase-deficient (dhfr-) cells by cotransformation with a dhfr minigene and amplified by selection for methotrexate resistance. The human ribosomal DNA was transcribed by RNA polymerase II, not RNA polymerase I or III. The metaphase chromosome regions containing the transcriptionally active human ribosomal DNA failed to show silver staining.
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PMID:Human ribosomal DNA fragments amplified in hamster cells are transcribed only by RNA polymerase II and are not silver stained. 243 41

A simple and nonradioactive gel retardation assay was established in order to separate weakly biotinylated nucleic acids according to the number of biotin molecules with which they are labeled. The method uses streptavidin to retard biotinylated RNA (Bio-RNA) in nondenaturing polyacrylamide gels; the streptavidin-Bio-RNA complexes are detected by silver staining. From the quantitative analysis of the band distribution, the average number of biotinylated nucleotides incorporated in a particular preparation may be calculated. The degree of biotinylation was analyzed with this method by studying the incorporation of Bio-4-UTP or Bio-11-UTP into RNA by in vitro transcription with T7 RNA polymerase. We found that both Bio-UTPs were incorporated into RNA by T7 polymerase three to four times less efficiently than unmodified UTP and that the average degree of biotinylation depended in a simple and calculable way on the Bio-UTP to total UTP ratio during transcription. Therefore, RNA transcripts with a defined average degree of biotinylation can be synthesized by T7 RNA polymerase simply by setting the Bio-UTP to total UTP ratio to the appropriate value. The gel retardation assay was also used to determine the average number and distribution of biotinyl residues in photobiotinylated RNA.
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PMID:Degree of biotinylation in nucleic acids estimated by a gel retardation assay. 247 60


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