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)

A crude RNA polymerase preparation was made from HeLa cells infected for 3 h with poliovirus. All virus-specific RNA species labeled in vitro (35S RNA, replicative intermediate RNA [RI], and double-stranded RNA [dsRNA]) would bind to poly(U) filters and contained RNase-resistant stretches of poly(A) which could be analyzed by electrophoresis in polyacrylamide gels. After incubation for 45 min with [3-H]ATP in the presence of the other three nucleoside triphosphates, the labeled poly(A) on the RI and dsRNA migrated on gels as relatively homogenous peaks approximately 200 nucleotides in length. In contrast, the poly(A) from the 35S RNA had a heterogeneous size distribution ranging from 50 to 250 nucleotides. In the absence of UTP, CTP, and GTP, the size of the newly labeled poly(A) on the dsRNA and RI RNA was the same as it was in the presence of all four nucleoside triphosphates. However the poly(A) on the 35S RNA lacked the larger sequences seen when the other three nucleoside triphosphates were present. When [3-H]ATP was used as the label in infected and uninfected extracts, heterogeneous single-stranded RNA sedimenting at less than 28S was also labeled. This heterogeneous RNA probably represents HeLa cytoplasmic RNA to which small lengths of poly(A) (approximately 15 nucleotides) had been added. These results indicate that in the in vitro system poly(A) can be added to both newly synthesized and preexisting RNA molecules. Furthermore, an enzyme capable of terminal addition of poly(A) exists in both infected and uninfected extracts.
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PMID:Polyadenylic acid on poliovirus RNA. III. In vitro addition of polyadenylic acid to poliovirus RNAs. 16 94

Treatment of neuroblastoma cells with dibutyryl-adenosine 3':5'-monophosphate or adenine induced axon formation and a three-fold increase in the polyadenylate, poly(A), content of the polysomal mRNA. The extracted poly(A) contained 90% adenylic acid and showed a mobility of 6--7 S in dodecylsulfate-polyacrylamide gel electrophoresis. Treatment with dibutyryl-adenosine 3':5'-monophosphate or adenine, also induced a 4--6 fold increase in a nuclear enzymic activity that incorporated [3H]ATP to an acid-insoluble polymer in a cell-free system. This polymer, like poly(A) extracted from the polysomal mRNA, was bound at high salt concentration to nitrocellulose filters. [3H]ATP incorporation was Mg2+-dependent, sensitive to ribonuclease and EDTA and resistant to deoxyribonuclease and actinomycin D. There was no incorporation of [3H]UTP or [3H]dTTP and addition of TUP, CTP and GTP did not increase the incorporation of [3H]ATP. 5-Bromodeoxyuridine induced axon formation of neuroblastoma cells and poly(A) polymerase activity, without increasing the poly(A) content in the polysomal mRNA. The results indicate that induction of axon formation of neuroblastoma cells is associated with an increase in the activity of poly(A) polymerase. It is suggested that the induction of this enzyme may be generally involved in cell differentiation.
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PMID:Induction of polyadenylate polymerase and differentiation in neuroblastoma cells. 17 99

Escherichia coli B infected with T4 phage ghosts at 10 mM Mg2+ regains its protein synthesizing activity upon addition of ATP, GTP, and their generator to approximately 2% of the intact exponentially growing cells. In contrast to amino acid incorporation by intact cells, this system is sensitive to EDTA or low Mg2+. On the other hand, this system, differing from the regular cell-free system, does not respond to addition of soluble protein and ribonuclease. The ghost-infected cells were able to synthesize beta-galactosidase upon addition of the inducer isopropyl thiogalactoside. The initial rate of the induction was 2.6% of intact cells. For this induction, the addition of cyclic AMP, amino acids, ATP, GTP, UTP, CTP, and their generator was necessary. The induction of beta-galactosidase in these ghost-infected cells was very sensitive to the addition of EDTA, CaCl2, sulfhydryl blocking reagent, rifampin and chloramphenicol but insensitive to DNA synthesis inhibitors such as nalidixic acid and DNase.
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PMID:Protein synthesis in bacteriophage ghost-infected cells. 17 55

Nuclei isolated from proliferating granulation tissue were incubated with 20 000 g supernatants from untreated and SiO2-treated subcellular particles of rat peritoneal macrophages in the presence of radioactive nucleic acid precursors. The supernatant from SiO2-treated subcellular particles increased the incorporation of [3H]CTP into nuclear RNA maximally by 26% at 5 min, and that of [methyl-3H]dTTP into DNA by 16% at 20 min. The release of radioactivity from labeled DNA was suppressed simultaneously. An RNase preparation from rat peritoneal macrophages enhanced the release of radioactivity from labeled DNA similarly as the soluble fraction from untreated subcellular particles of macrophages. The results suggest that the effects of the soluble fractions upon DNA metabolism of granuloma cells are at least partly independent of the effects on RNA metabolism and that the soluble fraction from SiO2-treated subcellular particles of macrophages stabilizes DNA through inhibition of nuclease activity.
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PMID:Effects of soluble fractions from untreated and SiO2-treated subcellular particles of macrophages on nucleic acid metabolism in isolated nuclei of experimental granulation tissue. 22 Aug 32

Transcription was determined in liver chromatin from rats fed for 6 days, an optimal (20%) or suboptimal (3%) amount of high-quality protein. Transcription by Escherichia coli RNA polymerase (EC 2.7.7.6) was lower after prolonged incubation with chromatin from rats fed 3% as compared with 20% protein. Differences were detected in the transcripts of the two types of chromatin after analysis by sucrose density gradient centrifugation. But no measurable differences were found in the melting profiles at low ionic strength of the two chromatin preparations. Transcription per milligram chromatin DNA was 25-fold higher using E. coli RNA polymerase instead of rat liver RNA polymerase II. The use of UTP as radioactive precursor in the absence of ATP, GTP and CTP resulted in a low labelling of RNA. One [lambda32P]UTP nucleotide was incorporated/8 UMP nucleotides. The product obtained was sensitive to ribonuclease treatment. In the presence of ATP, GTP and CTP [lambda-32P]UTP nucleotide incorporation was reduced and that of UMP nucleotide was increased giving a ratio of 1:188.
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PMID:Transcription of rat liver chromatin by Escherichia coli RNA polymerase: template properties after protein restriction. 36 67

A DNA . protein complex of about 150 S is isolated from purified spinach chloroplasts by Sepharose 4B gel filtration. A DNA-dependent RNA polymerase activity is found associated with the complex. This DNA protein complex is able to initiate RNA chains in vitro. The RNA synthesis is more dependent on CTP than other nucleoside triphosphates. 50% of the activity is still present with 0.6 M KCl. The temperature optimum occurs between 30 degrees C and 35 degrees C. Rifampicin and rifamycin SV have no inhibitory effect. TNA products have been characterized by gel filtration and by hybridization with chloroplast DNA (ctDNA). At the beginning of transcription DNA products are linked to the transcription complex and are later detached. The molecular weight of the product ranges between 0.07 X 10(6) and 2 X 10(6). A part of the product (3--4%) has a molecular weight higher than 2 X 10(6). No endogenous RNase activity was present during the molecular weight determinations experiments. Hybridization experiments show that at least 75% of the RNA products are hybridizable with ctDNA and that 40% of these products are composed of chloroplast ribosomal RNA, showing that rDNA is preferentially transcribed.
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PMID:Transcription activity of a DNA-protein complex isolated from spinach plastids. 46 44

Nuclei from seminal vesicle epithelium of adult guinea pigs were isolated in hypertonic sucrose solution. The incorporation of [3H]UTP by the isolated nuclei into acid-precipitable products was studied. Incorporation required ATP, GTP, CTP, UTP, and Mg+2. It was inhibited by addition of actinomycin D, deoxyribonuclease, or pyrophosphate to the reaction mixture. Thus, incorporation of [3H]UTP by isolated nuclei had the same characteristics that have been demonstrated for the reactions catalyzed by nuclear RNA polymerases. Using alpha-amanitin as a metabolic tool, we established concentrations of (NH4)2SO4. Mg+2, and nucleotides that give maximum assayable activities of nuclear RNA polymerases I and II. When the activities of polymerases I and II were measured in isolated seminal vesicle nuclei of guinea pigs that had been castrated 4 days earlier, a marked decrease in activities was found relative to control values (nuclei from intact animals). No further decrease was found 8 days after castration. Diminished accessibility to the nuclear DNA template and a decrease in the concentration of RNA polymerase molecules seemed to be responsible for the observed effects of castration on activities of RNA polymerases. An increase in ribonuclease activity did not seem to be responsible for the effects of castration. Activities of the enzymes did not change 2, 3, or 4 hours after intraperitoneal injection (2 mg/kg body weight) of each of five different androgens. Similarly, a single intraperitoneal injection of testosterone did not restore enzyme activity of polymerade I or II at any time during the first 24-hour period after hormone administration.
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PMID:RNA polymerase activities in isolated nuclei of guinea pig seminal vesicle epithelium: influence of castration and androgen administration. 90 9

Optimum conditions for in vitro RNA synthesis by the entomopoxvirus from Amsacta moorei, except for a temperature optimum of 26 degrees, were similar to those reported for vaccinia. Incorporation of 3H-ATP in the presence of CTP, GTP and UTP was significantly inhibited by actinomycin D; incorporation of 3H-ATP alone was not. The products formed by incorporation of 3H-ATP alone or with the three other nucleotides contained polyadenylic acid sequences. The sedimentation coefficient of the 3H-ATP-labeled product formed in the presence of CTP, GTP and UTP was reduced from 8-23S to 3-5S after RNase treatment. The product formed from 3H-ATP alone had an apparent sedimentation value of 3-5S.
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PMID:RNA polymerase activity of Amsacta moorei entomopox virions. 118 49

We evaluated the interaction of a biochemically active concentration of cyclopentenyl cytosine (CPE-C), an investigational antimetabolite which inhibits CTP synthetase, on the cytotoxicity of arabinosyl-5-azacytosine (Ara-AC) and 1-beta-D-arabinofuranosylcytosine (Ara-C) in HCT 116 colon carcinoma cells. A 3-h exposure to 0.5 microM CPE-C depleted CTP pools by over 90% and decreased dCTP pools by 57%; the effect on CTP pools persisted for up to 24 h following washout of CPE-C. A 3-h pre-exposure to 0.5 microM CPE-C augmented the growth inhibition resulting from a 24-h exposure to Ara-AC. The combination of 1 microM cytidine and deoxycytidine fully reversed the enhancement associated with CPE-C pretreatment, to a level of growth inhibition expected from either CPE-C or Ara-AC alone. A striking enhancement of toxicity was observed in clonogenic studies with pre-exposure to CPE-C at a nonlethal dose followed by either Ara-AC or Ara-C. CPE-C increased the formation of Ara-AC and Ara-C nucleotides by as much as 3-fold, and this was accompanied by increased incorporation of the arabinosyl nucleotides into methanol-precipitable material. Analysis of purified RNase-treated nucleic acids by cesium sulfate density centrifugation confirmed that a 3-h pre-exposure to CPE-C increased [3H]-Ara-C incorporation into DNA at 4 and 24 h by 2.4- and 2.7-fold, respectively. Thus, these studies indicate that CPE-C can function as a biochemical modulator. Following a brief exposure to a nonlethal concentration, CPE-C is capable of augmenting the cytotoxicity and intracellular metabolism of Ara-AC and Ara-C.
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PMID:Enhancement of the toxicity and DNA incorporation of arabinosyl-5-azacytosine and 1-beta-D-arabinofuranosylcytosine by cyclopentenyl cytosine. 169 59

Approximately one-third of the total ATP-hydrolysis activity in isolated HeLa nuclei is sensitive to RNAase (ribonuclease). This activity is selectively extracted with pulse-labelled RNA. In the extracts it co-sediments with various particles with sedimentation coefficients from 10S to 50S, but especially with 24S and 40S particles. ATP hydrolysis by the isolated particles was inhibited extensively (greater than 80%) by RNAase A, heparin and 0.2 M-NaCl. The activity of RNAase-treated particles was recovered when poly(A) was added, but not when DNA was added. The isolated particles exhibited RNAase-sensitive hydrolysis activities for dATP, GTP, CTP and UTP as well as for ATP, and the UTPase activity in the extracts showed nearly the same sedimentation distribution as the ATPase activity. When samples of isolated particles were irradiated with u.v. light in the presence of [alpha-32P]ATP, a 39 kDa polypeptide with a broad distribution from 10S to 50S like that of the ATPase and a 55 kDa polypeptide with a sharp distribution at 24S were photolabelled. Taken together, the data suggest that ATP-hydrolysis activity found in nuclear ribonucleoprotein subfractions appears to be the result of one or two RNA-dependent NTPases that are normally associated with endogenous RNA in a wide variety of particles.
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PMID:Characterization of a ribonuclease-sensitive nucleoside triphosphatase activity from HeLa nuclei. 240 2


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