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

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Query: EC:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nuclear matrices were isolated by treatment of isolated HeLa cell nuclei with high DNase I, pancreatic RNase and salt concentrations. ADP-ribosylated nuclear matrix proteins were identified by electrophoresis, blotting and autoradiography. In one experimental approach nuclear matrix proteins were labeled by exposure of permeabilized cells to the labeled precursor [32P]NAD. Alternatively, the cellular proteins were prelabeled with [35S]methionine and the ADP-ribosylated nuclear matrix proteins separated by aminophenyl boronate column chromatography. By both methods bands of modified proteins, though with differing intensities, were detected at 41, 43, 46, 51, 60, 64, 69, 73, 116, 140, 220 and 300 kDa. Approximately 2% of the total nuclear ADP-ribosyltransferase activity, but only 0.07% of the nuclear DNA, was tightly associated with the isolated nuclear matrix. The matrix-associated enzyme catalyzes the incorporation of [32P]ADP-ribose into acid-insoluble products of molecular mass 116 kDa and above, in a 3-aminobenzamide-inhibited, time-dependent reaction. The possible function of ADP-ribosylation of nuclear matrix proteins and of the attachment of ADP-ribosyltransferase to the nuclear matrix in the regulation of matrix-associated biochemical processes is discussed.
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PMID:Modification of nuclear matrix proteins by ADP-ribosylation. Association of nuclear ADP-ribosyltransferase with the nuclear matrix. 300 Jul 77

Verticillium agaricinum when grown for 60 min under near-UV irradiation (366 nm) followed by 24 h in darkness produced maximal activity of a number of nucleic acid enzymes (DNase I, endonuclease, nuclease, RNase A, and RNase T1). Total protein and nucleic acid on the other hand showed a decrease under the same conditions. The nucleic acid enzymes which are involved in reversible reactions seem to favour nucleic acid degradation in this study.
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PMID:Effect of near-UV (366 nm) on the activity of certain nucleic acid enzymes in Verticillium agaricinum. 300 7

Using S1 nuclease protection assays, we have examined the representation of cell cycle-dependent H4 histone RNAs in the nuclear matrix and nonmatrix nuclear fractions of human cells. Cytoplasmic and nuclear fractions were prepared from exponentially growing HeLa S3 cells by double detergent (sodium deoxycholate and NP40) lysis. The nuclear matrix and nonmatrix nuclear fractions were then prepared by digestion of nuclei with RNase-free DNase I and subsequent high-salt [0.4 M (NH4)2SO4] extraction. Subcellular fractions were characterized by 1) DNA, RNA, and protein composition; 2) electrophoretic analysis of the proteins in each fraction; 3) the representation of 45S ribosomal RNA precursors and processed 18S and 28S ribosomal RNAs; and 4) the presence of mitochondrial RNAs. In contrast to ribosomal and messenger RNA precursors, which are largely associated with the nuclear matrix, the human H4 histone RNAs in the nucleus were found predominantly in the nonmatrix nuclear fraction. The presence of H4 histone RNA in the nonmatrix nuclear fraction appeared to be coupled to DNA replication, since inhibition of DNA synthesis by hydroxyurea resulted in a loss of histone RNA from the nucleus. Our results suggest either that the association of histone RNAs with the nuclear matrix is very transient or that posttranscriptional modifications of the rapidly processed histone gene transcripts do not involve the nuclear matrix.
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PMID:Localization of human histone gene transcripts predominantly in the nonmatrix nuclear fraction. 301 90

The human proliferation-associated nucleolar antigen p120 was localized to substructures within HeLa cell nucleoli by immunofluorescence and immunoelectron microscopy of cells whose nucleoli were segregated by drug treatment or extracted with nucleases. By indirect immunofluorescence, protein p120 was localized diffusely throughout all interphase nucleoli. However, high resolution immunoelectron microscopy demonstrated that protein p120 staining delineated a network of 20-30-nm diameter beaded fibrils distributed throughout the nucleolus. This distribution was unique compared to that of the nucleolar proteins p145, RNA polymerase I, or B23 which were examined simultaneously. Drug-induced segregation of nucleoli by actinomycin D or dichlorobenzimidazole riboside, followed by immunoelectron microscopy, indicated that protein p120 was concentrated at the periphery of the granular region in segregated nucleoli. In situ nuclease digestion of cells with DNase I and/or RNase A did not release p120 from the nucleolus. Instead, p120 immunoreactivity was retained within phase-dense residual nucleoli. These results provide evidence that protein p120 is associated with, and in fact delineates, a network of fibrils which is retained in the nucleolar residue fraction of proliferating cells.
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PMID:Intranucleolar localization of human proliferating cell nucleolar antigen p120. 305 5

Examination of the intestinal contents of free-living Oryzomys nigripes rats by PAGE revealed two sharply defined bands that could be stained by ethidium bromide or by silver nitrate with comparable intensities. The molecules forming these bands were susceptible to digestion by pancreatic RNase A but not by RNase T1 or by DNase I. Their lengths were estimated to be about 2.6 and 1.5 kbp, respectively, by comparison with rotavirus SA11 genome segments. They cosedimented in CsCl gradients at a density of 1.39 to 1.40 g/ml, together with uniform particles approximately 35 nm in diameter with indistinct surface structure. It is suggested that these particles represent an as yet undescribed virus with a bisegmented double-stranded RNA genome, for which the name 'picobirnavirus' is proposed.
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PMID:A virus with a bisegmented double-stranded RNA genome in rat (Oryzomys nigripes) intestines. 305 86

The change of human nuclear antigen expression in proliferating cells recognized by a monoclonal antibody, Ki-67, during the cell cycle was investigated in HeLa S3 cells using a bivariate-flow-cytometric analysis. The antigen was immunocytochemically stained with FITC, and DNA was stained with propidium iodide (Pl). The expression of the antigen increased with cell-cycle progression, especially in the latter half of S-phase and reached a maximum at G2M-phase, although its content varied greatly from cell to cell. The cells in which DNA synthesis was inhibited by treatment with hydroxyurea increased markedly in the antigen expression (as compared to untreated cells). Treatment with adriamycin also elevated the antigen content. After digestion with DNase I, but not after RNase treatment, FITC fluorescence from the antigen disappeared. These results suggest that the Ki-67 antigen is bound to DNA and its expression does not depend on DNA replication. Although the biological implications of the antigen remain unresolved, the antigen may be considered to be essential for maintaining the proliferating state of cells.
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PMID:The cell cycle associated change of the Ki-67 reactive nuclear antigen expression. 312 42

Abnormal tubulofilamentous structures have been identified in electron micrographs of thin sections and negatively stained impression grids prepared from brains of animals with scrapie and other spongiform encephalopathies, and we showed that such tubules contain a core of filamentous structures resembling scrapie-associated fibrils (SAF). We treated impression grids from brains of scrapie-infected hamsters with several substances that bind to or cleave proteins and nucleic acids to see if they had any effect on the abnormal tubulofilamentous structures. Treatment with three proteolytic enzymes reduced the caliber of the tubules from about 50 nm to 30 nm; subsequent treatment of the 30-nm tubules with DNase I left many typical SAF as well as transitional forms in which twisted SAF emerged from tubules. DNase treatment of the original thicker tubules had no effect, and no SAF were seen on grids. Treatment of the 30-nm tubules with any of three other nucleases (micrococcal, mung bean, and BAL-31) also produced SAF. However, treatment with RNase A had no effect either on the original 50-nm tubules or on the 30-nm tubules produced by proteolysis. Detergent treatment of any of the preparations produced SAF. Treatment with ethidium bromide resulted in staining of the tubules that was inhibited by magnesium ions. The data suggest that the abnormal tubulofilamentous particles found in spongiform encephalopathies may consist of an outer cylinder of protein, an inner cylinder of DNA, and an innermost core of SAF.
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PMID:Evidence that DNA is present in abnormal tubulofilamentous structures found in scrapie. 313 Jun 30

We used the DNase I-hypersensitive sites around the mouse acetylcholine receptor delta-subunit gene as a guide toward the cloning and sequencing of delta and gamma transcriptional regulatory regions and as a means to assess chromatin structural activation of the delta- and gamma-subunit genes during myogenesis. Genomic cloning of hypersensitive sites downstream of the delta-subunit gene revealed the presence of the gamma-subunit gene approximately 5 kilobases away; the hypersensitive sites mapped to the 5' end of the gamma-subunit gene. Sequence comparison of restriction fragments containing hypersensitive sites in analogous locations at the 5' ends of the delta- and gamma-subunit genes uncovered little overall homology between the two genomic fragments; however, an 11- of 13-base-pair match between the two sequences was found. Homologs to this sequence were also found to be present in the upstream regions of the chicken alpha- and mouse beta-subunit genes. By RNase protection and primer extension analyses, the delta-subunit gene transcription start site was mapped to 56 base pairs upstream of the initiator ATG codon. Clonal cell lines with various potentials to differentiate to the skeletal muscle phenotype were examined for their hypersensitive site pattern within the delta-gamma locus. Only remote hypersensitive sites flanking the locus appear in pluripotential mesodermal cells. A cell line of determined but inducible myoblasts expressed only one more intergenic site, while in permissively differentiating myoblasts hypersensitive sites were already present at the 5' ends of the delta and gamma genes prior to differentiation. Terminal differentiation resulted in an identical pattern of hypersensitive sites in all muscle cell lines examined so far, with an intergenic site near the gamma-subunit gene being the only site specific to the differentiated muscle phenotype.
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PMID:Stepwise activation of the mouse acetylcholine receptor delta- and gamma-subunit genes in clonal cell lines. 324 54

Nontoxigenic strains of Clostridium botulinum types C and D are converted to toxigenic strains by infection with specific Tox+ bacteriophages. The nucleic acids were extracted from five converting phages, c-st, c-468, c-203, c-d6f, and d-1873, and one nonconverting phage, c-n71, and treated with nucleases. The nucleic acids isolated were not digested by RNase A, but were digested by DNase I and exonuclease III, indicating that they were double-stranded DNA. On the basis of the restriction endonuclease digestion patterns on 0.8% agarose gel electrophoresis, the length of c-st, c-n71, c-468, and c-d6f phage DNAs was estimated to be about 110 kilobase pairs and that of c-203 and d-1873 was about 150 kilobase pairs. The digestion patterns of c-st, c-468, and c-n71 phage DNAs by PstI and HindIII were very similar. High homology was observed in the dot hybridization test. For other phages and nucleases, a good similarity was not observed. Only a little similarity was observed between c-203 and c-d6f phages. The existence of the structural genes for the toxin in both c-st and c-n71 phages was confirmed by the hybridization test with these phage DNAs and the oligonucleotide probe which represented the DNA sequence predicted for the N-terminal amino acids (2 to 17) of C. botulinum type C toxin. The loss of the converting ability of c-n71 phage may be caused not by the deletion of the tox+ gene but rather by the base mutation in c-st phage DNA.
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PMID:Characterization of bacteriophage nucleic acids obtained from Clostridium botulinum types C and D. 327 90

A cell-free system was used to characterize the binding reaction between the progesterone receptor and nuclear acceptor sites prepared from rat placenta. Two forms of receptor-acceptor complex were examined. One was extracted from nuclei by exposure to 0.6 M KCl; the other type was resistant to salt extraction. Kinetic analysis indicated that the binding reactions were saturable (3-4 pmol binding sites/mg DNA) and of high affinity (Kd = 3-6 nM). Acceptor binding was specific for placental nuclei and did not occur with nuclei prepared from spleen or with denatured nuclei from placenta. Acceptor sites were further characterized by their sensitivity to RNase, DNase I, and protease. RNase treatment had no influence on receptor-acceptor binding. However, DNase I reduced the number of KCl-resistant acceptor sites by 41%, but only a 19% reduction occurred in KCl-extractable acceptor sites (P less than 0.05). Protease removed 34% and 48% of the KCl-resistant and -extractable acceptor sites, respectively, and combined treatment with DNase and protease eliminated 76% of acceptor-binding activity. The endogenous inhibitor previously described from rat placental cytosol blocked acceptor-binding sites in a concentration-dependent manner, a decrease of 1.15 pmol sites/mg inhibitor protein for resistant sites and 0.76 pmol/mg inhibitor protein for extractable sites. However, receptor-acceptor binding was not altered by treating nuclei with actinomycin D or chloroquine. Mercurial reagents reduced receptor-acceptor interaction by 80% and 94% in KCl-resistant and -extractable sites, respectively, whereas sulfhydryl alkylating agents reduced binding 35% and 76%. Pyridoxal phosphate destroyed 88-93% of acceptor binding. The results of these studies suggest that the progesterone receptor acceptor sites are composed of a complex of chromatin protein and DNA in rat placenta. Furthermore, the binding reaction requires the participation of sulfhydryl and terminal amino groups.
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PMID:Nuclear acceptor sites for progesterone-receptor complexes in rat placenta. 329 40


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