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:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Influenza virus ribonucleoprotein complexes isolated from MDCK-infected cells have been used to optimize transfection conditions of MDCK cells. Ribonucleoprotein complex-mediated infection was strictly dependent on pretreatment of the cell cultures, resistant to mild NP40 treatment and sensitive to RNase treatment. Under optimal conditions, up to 10(4) plaque forming units per microgram of viral RNA could be obtained.
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PMID:Transfection of MDCK cells with influenza virus ribonucleoprotein complexes. 327 Oct 63

The binding sites for influenza viral RNA polymerase on genome RNA segments were investigated. Ribonucleoprotein (RNP) cores containing the RNA polymerase were isolated from detergent-treated virions by glycerol gradient centrifugation. On ApG-primed in vitro transcription by the isolated RNP cores, different levels of RNA transcripts were synthesized for the eight RNP cores, suggesting an uneven distribution of the RNA polymerase. 3'-Terminal labeling of the RNP cores with the use of [32P]pCp and T4-RNA ligase indicated a reciprocal correlation between the levels of the RNA-3' label and RNA synthesis. Centrifugation of detergent-treated virions in a double gradient of cesium trifluoroacetate (or cesium chloride) and glycerol yielded RNA polymerase-RNA complexes devoid of NP, the major RNA-bound protein, but the pattern of RNA-3' labeling remained virtually unaffected. All these observations together indicated that the RNA polymerase is associated near the 3' termini of some viral RNA segments, thereby preventing the in vitro labeling of the RNA-3' ends. The results of foot-printing experiments using RNase V1 and RNase T2 were in agreement with this model.
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PMID:Identification of the RNA polymerase-binding site on genome RNA of influenza virus. 343 66

From soluble proteins of influenza A viruses the author isolated, partially purified, and concentrated an inhibitor of host serum RNase, possessing no infectivity or neuraminidase activity, having the virus-specific antigen and, apparently, a lipoprotein composition, inhibiting RNAse activity by forming a complex with the enzyme and substrate, and considered to be one of the factors of virus pathogenicity acting on the molecular level. Antigenic relationships between RNase inhibitors of hierarchically remote influenza viruses were found. Immunization of mice with the inhibitor antigen prevents inhibition of serum RNAse activity after infection, and vaccination with the inhibitor antigen in combination with whole-virion killed vaccine significantly increased the protective effectiveness of the artificial immunity in experiments. The inhibitor preparation obtained is anaphylactogenic.
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PMID:[Influenza inhibitor of the host serum RNAse]. 379 7

Nuclei purified from chicken embryo fibroblast cells infected with influenza (fowl plague) virus contain an RNA-dependent RNA polymerase. The in vitro activity of this enzyme is insensitive to actinomycin D, and is completely destroyed by preincubation with ribonuclease. Enzyme induction is prevented if cells are treated with actinomycin D or cycloheximide at the time of infection. RNA-dependent RNA polymerase activity increases rapidly in cell nuclei from 1 h postinfection, reaches a maximum at 3 to 4 h, then declines; a similar RNA polymerase activity in the microsomal cell fraction increases from 2 h postinfection and reaches a maximum at 5 to 6 h. The characteristics of the nuclear and microsomal enzymes in vitro are similar with respect to pH and divalent cation requirements. The in vitro products of enzyme activity present in the nuclear and microsomal fractions of cells infected for 3 and 5 h were characterized by sucrose density gradient analysis, and annealing to virion RNA. The microsomal RNA polymerase product contained 67 and 93% RNA complementary to virion RNA at 3 and 5 h, respectively; for the nuclear RNA polymerase product these values were 40% in each case.
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PMID:RNA-dependent RNA polymerase in nuclei of cells infected with influenza virus. 435 67

Influenza B/LEE/40, B/Rome/1/67, B/Hong Kong/8/73, and B/Victoria/98926/70 viruses have a similar polypeptide composition as analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. These viruses are composed of six or seven polypeptides, depending on whether one or two high-molecular-weight polypeptides are resolved, ranging in molecular weights from 27,000 to 90,400. Three of these polypeptides, namely the heavy and light hemagglutinin chains and the neuraminidase, have attached carbohydrate. Highly purified influenza B/LEE/40 and B/Rome/1/67 virus preparations have RNA-dependent RNA polymerase activity equivalent to the incorporation of 100 and 30 pmol, respectively, of (3)H-UMP per mg of virus protein per h at 37 C, which is demonstrated only in detergent-treated virus suspensions. However, no RNA-dependent DNA polymerase enzyme activity was detected in the two viruses although virus suspensions were "activated" by heat, alpha-chymotrypsin, and detergents. Other enzymatic activities were associated with purified preparations of influenza B virus and were attributed to minor contamination of virus with host cell enzymes. Thus, nucleoside and deoxynucleoside phosphohydrolase enzymes were active in the absence of detergents and catalyzed the release of 1,200 and 1,800 nmol of P(i) per mg of virus protein in 30 min at 37 C from ATP and dATP substrates. Thin-layer chromatography indicated that the products of the phosphohydrolase enzymes of influenza B/LEE/40 were mainly nucleoside diphosphate and monophosphate. The latter enzymes were tightly bound to influenza B/LEE/40 virus and could not be removed completely by repeated centrifugation, including centrifugation of the virus to equilibrium in density gradients of 25 to 40% (wt/vol) cesium chloride. A low degree of RNase (approximately 0.01 mug% contamination) and phosphatase (10-30 nmol of P(i) released per mg of virus protein per 30 min) activity was detected in some, but not all, influenza B/LEE/40 virus preparations.
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PMID:Polypeptide composition of Influenza B viruses and enzymes associated with the purified virus particles. 435 55

The properties of the ribonucleic acid (RNA) synthesized by the influenza (WSN) virion polymerase have been investigated. Most of the product RNA is synthesized in association with virion RNA species from which it can be released by heat treatment as single-stranded, ribonuclease-sensitive polynucleotides (average molecular weight, 2-hr sample, about 10(5) daltons). At least 95% of the product is complementary to the viral RNA species. On the basis of the molar ratio of the RNA species isolated from a (3)H-uridine-labeled virus preparation, it was calculated that the WSN genome consists of seven pieces of RNA with a sum molecular weight of about 5 x 10(6) daltons.
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PMID:Transcription of the influenza ribonucleic acid genome by a virion polymerase. II. Nature of the in vitro polymerase product. 510 47

A ribonuclease-resistant ribonucleic acid (RNA) with a sedimentation coefficient of 12S was obtained by self-annealing influenza virus-specific RNA isolated from infected cells. It had the properties of double-stranded RNA. (i) Sedimentation behavior in sucrose gradient was independent of salt concentration. (ii) Thermal transition profile was sharp; the melting temperature is 83 C in 0.1 SSC (0.15 m NaCl plus 0.015 m sodium citrate) and 98 C in SSC. (iii) Buoyant density in cesium sulfate was 1.58 g/cm(3) compared to 1.64 g/cm(3) for single-stranded RNA. (iv) It gave rise to single-stranded RNA after denaturation. (v) The 12S RNA duplex contained both plus and minus strands of influenza virus. Labeled plus strands could be displaced by extraneous cold plus strands and extraneous (32)P-labeled plus strands could be incorporated into duplex after denaturation and reannealing.
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PMID:Characterization of influenza virus ribonucleic acid duplex produced by annealing in vitro. 581 52

Experimentally, by stimulation of the activity of serum DNase and RNase direct evidence of their nonspecific protective role in herpes and influenza infections, respectively was obtained. Potentiation of the protective effect upon interaction of endogenous and exogenous nucleases with specific antibodies was demonstrated. Experiments in mice and observations in humans established a marked inhibition of serum RNase activity due to binding with the inhibitor, in mild and severe forms of influenza in nonimmune hosts and host immunized with live and inactivated vaccines. This is assumed to be one of the causes of insufficient effectiveness of artificial immunity against influenza.
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PMID:[Serum nucleases as nonspecific antiviral factors and their role in artificial anti-influenza immunity]. 608 98

Two enzymatic activities hydrolysing ribonucleoside 2', 3'-cyclic phosphates (2', 3'-cNMP) to 2'- or 3'- nucleoside monophosphate were found associated with influenza and Newcastle disease viruses. The two enzymatic activities differed from each other by temperature optima and thermoresistance. 2', 3'-Cyclic nucleotide 3'-phosphohydrolase was responsible for splitting of the substrate to 2'-NMP. Splitting of the substrate to 3'-NMP was due either to ribonuclease or to 2', 3'-cyclic nucleotide 2'-phosphohydrolase.
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PMID:Hydrolysis of ribonucleoside 2',3'-cyclic phosphates by influenza and Newcastle disease viruses. 611 52

The sequence of 2,191 nucleotides encoding the env gene of murine retrovirus Akv was determined by using a molecular clone of the Akv provirus. Deduction of the encoded amino acid sequence showed that a single open reading frame encodes a 638-amino acid precursor to gp70 and p15E. In addition, there is a typical leader sequence preceding the amino terminus of gp70. The locations of potential glycosylation sites and other structural features indicate that the entire gp70 molecule and most of p15E are located on the outer side of the membrane. Internal cleavage of the env precursor to generate gp70 and p15E occurs immediately adjacent to several basic amino acids at the carboxyl terminus of gp70. This cleavage generates a region of 42 uncharged, relatively hydrophobic amino acids at the amino terminus of p15E, which is located in a position analogous to the hydrophobic membrane fusion sequence of influenza virus hemagglutinin. The mature polypeptides are predicted to associate with the membrane via a region of 30 uncharged, mostly hydrophobic amino acids located near the carboxyl terminus of p15E. Distal to this membrane association region is a sequence of 35 amino acids at the carboxyl terminus of the env precursor, which is predicted to be located on the inner side of the membrane. By analogy to Moloney murine leukemia virus, a proteolytic cleavage in this region removes the terminal 19 amino acids, thus generating the carboxyl terminus of p15E. This leaves 15 amino acids at the carboxyl terminus of p15E on the inner side of the membrane in a position to interact with virion cores during budding. The precise location and order of the large RNase T(1)-resistant oligonucleotides in the env region were determined and compared with those from several leukemogenic viruses of AKR origin. This permitted a determination of how the differences in the leukemogenic viruses affect the primary structure of the env gene products.
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PMID:Nucleotide sequence of the Akv env gene. 628 70


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