Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Particulates with the properties of cores and/or ribonucleoproteins of RNA tumor viruses have been isolated from Sterox-SL-treated fractions of murine and human mammary adenocarcinomas. These particulates have an RNA-directed DNA polymerase, a 60 to 70 S RNA, and a density of 1.26 g/ml or greater in sucrose equilibrium density gradients. Their uniquely higher densities lead to banding in regions comparatively free of cellular contaminants. These circumstances minimize some of the technical complications of performing the simultaneous detection assay in the presence of cell debris.
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PMID:Biochemical characterization of putative subviral particulates from human malignant breast tumors. 4 81

Microwave-induced emission spectrometry combined with gel-exclusion chromatography provides a microanalytical system capable of precisely measuring 10 minus 10 to 10 minus 13 g of metal in microgram amounts of enzyme. Such sensitivity greatly exceeds that of other, more conventional methods. Metal quenching agents and low-molecular-weight protein contaminants were removed from the enzyme by Sephadex G-100 chromatography in microbore columns (0.03 times 25 cm). Droplet fractions were analyzed for zinc by the present method, for enzyme activity, and for protein content. With this analytical system we could demonstrate that stoichiometric amounts of zinc are present in the RNA-dependent DNA polymerase, the reverse transcriptase, from wooly monkey type C RNA tumor virus. The precision of the method for zinc was demonstrated by the coefficient of variation of 4.4 percent for 10 mug of zinc per liter. Validity and accuracy of the method were established by determining zinc in a series of zinc metalloenzymes of known metal content and stoichiometry.
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PMID:Microanalytical system for determination of picogram quantities of metals in metalloenzymes, as illustrated with zinc-containing enzymes. 4 97

Two RNase H (RNA-DNA hybrid ribonucleotidohydrolase, EC 3.1.4.34) activities separable by Sephadex G-100 gel filtration were identified in lysates of Moloney murine sarcoma-leukemia virus (MSV). The larger enzyme, which we have called RNase H-I, represented about 10% of the RNase H activity in the virion. RNase H-I (i) copurified with RNA-directed DNA polymerase from the virus, (ii) had a sedimentation coefficient of 4.4S (corresponds to an apparent mol wt of 70,000), (iii) required Mn-2+ (2 mM optimum) for activity with a [3-h]poly(A)-poly(dT) substrate, (iv) eluted from phosphocellulose at 0.2 M KC1, and (v) degraded [3-H]poly(A)-poly(dT) and [3-H]poly(C)-poly(dG) at approximately equal rates. The smaller enzyme, designated RNase H-II, which represented the majority of the RNase H activity in the virus preparation, was shown to be different since it (i) had no detectable, associated DNA polymerase activity, (ii) had a sedmimentation coefficient of 2.6S (corresponds to an apparent mol wt of 30,000), (iii) preferred Mg-2+ (10 to 15 mM optimum) over Mn-2+ (5 to 10 mM optimum) 2.5-fold for the degradation of [3-H]poly(A)-poly(dT), and (iv) degraded [3-H]poly(A)-poly(dT) 6 and 60 times faster than [3-H]poly(C)-poly(dG) in the presence of Mn-2+ and Mg-2+, respectively. Moloney MSV DNA polymerase (RNase H-I), purified by Sephadex G-100 gel filtration followed by phosphocellulose, poly(A)-oligo(dT)-cellulose, and DEAE-cellulose chromatography, transcribed heteropolymeric regions of avian myeloblastosis virus 70S RNA at a rate comparable to avian myeloblastosis virus DNA polymerase purified by the same procedure.
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PMID:Purification and characterization of the DNA polymerase and RNase H activities in Moloney murine sarcoma-leukemia virus. 4 24

The 2'-azido analogs of poly(U) and poly(C), poly(dUz) [poly(2'-azido-2'-deoxyuridylic acid)], and poly-(dCz [poly(2'-azido-2'-deoxycytidylic acid)], were found to inhibit the RNA-directed DNA polymerase (reverse transcriptase) activity of murine leukemia (Moloney, Rauscher) and sarcoma (Moloney) virus, and feline leukemia (Theilen) and sarcoma (Gardner) virus, while under the same conditions the unsubstituted parent compounds failed to do so. In addition, poly(dUz) and poly(dCz) inhibited the replication of exogenous murine sarcoma virus (Moloney) in nontransformed cells (as assessed by an infectious center assay), but poly(dUz) failed to suppress the formation of endogenous sarcoma and leukemia viruses in transformed cell lines (MO-P, JLSV5). In these same cells, poly(dUz) failed to inhibit the multiplication of vesicular stomatitis virus. These data add further strength to the contention that reverse transcriptase is necessary for the productive infection and transformation of normal cells by oncornaviruses but is not essential maintenance of this transformed state and the continuous production of new viruses particles by these transformed cells.
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PMID:Inhibition of oncornavirus functions by 2'-azido polynucleotides. 4 74

Radioactive anti-messenger DNA (3H-cDNA) complementary to silk fibroin mRNA has been synthesized using reverse transcriptase. This 3H-cDNA has been found to be a specific and sensitive probe for the detection of fibroin genes in the genome of Brombyx mori. Actinomycin-CsCl gradients give a large separation of the high GC fibroin genes from the bulk DNA. This density shift of fibroin genes has been measured as a function of DNA molecular weight. The data support a model in which a single high GC fibroin gene of 11.6 times 10-6 daltons is surrounded by at least 6 times 10-7 daltons of low GC DNA (30-39 percent). This finding, along with saturation hybridization studies (Suzuki, Gage, and Brown, 1972), demonstrate that the fibroin gene is present in a single copy per haploid genome.
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PMID:The length of the fibroin gene in the Bombyx mori genome. 4 71

Rabbit globin mRNA was copied by AMV reverse transcriptase in the presence of various concentrations of deoxyribonucleotides (dNTPs). The cDNAs were analyzed by electrophoresis under denaturing conditions in formamide-polyacrylamide gels. Discrete size products were detected, ranging from 65 to 650 nucleotides-that is, up to the full length of the mRNA template. Increasing the concentrations of all four dNTPs stimulated formation of full-length transcripts and made the incomplete copies less abundant. Hybridization and nuclease digestion experiments indicated that the full-size product is indeed a complete transcript of globin mRNA. Similar results were obtained with chorion mRNAs. The possible usefulness of the discrete partial transcripts is discussed.
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PMID:Full length and discrete partial reverse transcripts of globin and chorion mRNAs. 4 72

Dexamethasone (1,4-pregnadiene-9-fluor-16alpha-methyl-11beta,17alpha,21-triol-3,20-dione), a potent synthetic glucocorticoid, stimulates mouse mammary tumor virus expression 10- to 20-fold in tissue culture cells. This hormone effect was observed at concentrations as low as 1 times 10-10 M and was maximal at 10-7 to 10-8 M. The time course of induction indicated that detectable increases in extracellular viral DNA polymerase were first noted 18 to 24 hours following the addition of dexamethasone, and cells produced the highest polymerase levels at the time monolayers approached confluence. Steroid responsiveness was associated with specific increases in type B murine mammary tumor virus structural polypeptide (gp52(sl) expression and murine mammary tumor virus RNA that quantitatively paralleled the increase in extracellular virus production as measured by electron microscopy and supernatant RNA-dependent DNA polymerase activity. Another virally transformed murine cell line, KA 31, did not contain detectable levels of murine mammary tumor virus gp52(sl) or RNA before or after dexamethasone stimulation; thus induction was noted only in murine cells with pre-existing murine mammary tumor virus expression. No increase in basal levels of type C murine leukemia viral proteins or RNA was detected in dexamethasone-treated mammary cell lines which were producing increased levels of murine mammary tumor virus. Therefore, increases in murine mammary tumor virus gene products are specific for murine mammary tumor virus DNA sequences under these conditions.
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PMID:Mammary tumor virus induction by glucocorticoids. Characterization of specific transcriptional regulation. 4 26

This report provides a more rigorous proof of previous findings that the RNA transcribed in vitro from the chromatins of different organs shows different sequence specificities. Here the particular case of the globin gene is considered for a comparison of embryonic mouse liver chromatin and mouse brain chromatin using the reverse transcriptase cDNA copy of globin 9S m RNA as a definitive probe. It can be shown that globin sequences are transcribed in vitro from embryonic liver chromatin and not brain chromatin. This specificity in liver chromatin can be reconstituted after dissociation of the structural elements of the chromatin. It can be shown that the non-histone protein fraction of liver chromatin can confer specificity for the transcription of globin sequences from brain chromatin which otherwise lacks this ability. Preliminary results are described with the Friend cell system, in which haemoglobin synthesis can be induced in vitro in the presence of dimethylsulphoxide.
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PMID:Control of transcription of the globin gene. 4 32

9-O-methyloximd erythromycin A and its analogue inhibited reverse transcriptase and blocked focus formation of Rous sarcoma virus. These chemicals inhibited neither DNA-dependent DNA polymerase nor DNA-dependent RNA polymerase from bacterial sources. However, they inhibited reverse transcriptase with an apparently differnt mechanism than that by rifamycin ABDP.
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PMID:Oxime derivatives of erythromycin: inhibitors of Rous sarcoma virus reverse transcriptase activity and focus formation. 4 82

A hamster syncytium-forming ("foamy") virus (HFV) was characterized. The HFV sedimented in isopyknic sucrose density gradients at 1.16-1.165 g/ml. It had RNA but no DNA, its replication was inhibited by actinomycin D, and it contained virion-associated, RNA-dependent DNA polymerase. Analysis of the RNA from purified virus showed several species: 62S, 40S, 28-30S, 18-20S, and 4-7S.
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PMID:Biochemical properties of a hamster syncytium-forming ("foamy") virus. 4 98


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