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)

The present study describes the separation and purification of a reverse transcriptase and cellular DNA polymerases from the human spleen of a patient with myelofibrotic syndrome. The specific requirements with respect to bivalent cations and template-primers for DNA polymerase-alpha, DNA polymerase-beta and DNA polymerase-gamma, as well as for the reverse transcriptase, are reported. Sedimentation-velocity measurements of the purified enzymes gave values of 150000, 40000, 100000 and 70000 daltons for DNA polymerase-alpha DNA polymerase-beta, DNA polymerase-gamma and the reverse transcriptase respectively. Serological studies have shown that the reverse transcriptase from human spleen is not antigenically related to cellular DNA polymerase-alpha, -beta or -gamma, but is antigenically related to reverse transcriptase from simian sarcoma virus and gibbon-ape leukaemia virus.
Biochem J 1977 Dec 01
PMID:Purification, biochemical characterization and serological analysis of cellular deoxyribonucleic acid polymerases and a reverse transcriptase from spleen of a patient with myelofibrotic syndrome. 7 8

Poly (2-methylthioinosinic acid) [poly(ms2I)] was found to markedly inhibit the RNA directed DNA polymerase (reverse transcriptase) activity of murine (Moloney, Rauscher) leukemia virus and murine (Moloney) sarcoma virus, while under the same conditions the unsubstituted parent compound poly(I) showed little, if any, inhibitory effect. Copolymers of inosinic acid (I) and 2-methylthioinosinic acid2(ms2I) showed an intermediary effect, depending on the I:ms2I ratio. Poly(ms2I) also inhibited the transformation of normal cells by murine (Moloney) sarcoma virus, as assessed by an infectious center assay.
Nucleic Acids Res 1975 Dec
PMID:Inhibition of oncornavirus functions by poly (2-methylthioinosinic acid). 7 96

Reverse transcription of 70S AMV RNA by AMV reverse transcriptase has been studied in the presence of E. coli tRNAs. We have shown that inhibition of DNA synthesis occurs and that the tRNAs bind to the enzyme and not to the 70S RNA. The results have implications for the control of reverse transcription in vivo.
Nucleic Acids Res 1975 Dec
PMID:E. coli tRNAs as inhibitors of viral reverse transcription in vitro. 7 97

An RNA-direct DNA polymerase was purified from human melanoma tissue by successive column chromatography on DEAE-cellulose (DE-23 and DE-52) and phosphocellulose. The purified reverse transcriptase has a mol. wt. of 68,000, a pH optimum of 8.0, a Mn2+ optimum of 0.6 mM, and a KCl optimum of 60 mM. The purified enzyme transcribes (rA)n - (dT)12, (rC)n - (dG)18, (Ome-rC)n - (dG)18 and a 70s RNA from Rauscher leukemia virus (RLV), but failed to transcribe (dA)n - (dT)12. This enzyme has no terminal deoxynucleotidyl transferase activity. Serological studies have shown that the reverse transcriptase from human melanoma tissue is antigenically not related to DNA polymerases from Simian sarcoma virus (SiSV), Avian myeloblastosis virus (AMV), RLV, and human spleen of a patient with myelofibrosis. The purified enzyme showed a close antigenic resemblance to DNA polymerases from baboon endogenous virus (BEV) and rhabdomyosarcoma virus (RD-114), the endogenous virus of the cat.
Cancer Lett 1978 Dec
PMID:Biochemical and immunological characterization of a reverse transcriptase from human melanoma tissue. 8 88

We have isolated a nonconditional mutant of PR-RSV-E with unique properties. This virus (SE 21Q1b) is shed from a continuously growing culture of transformed quail cells. 21Q1b virions are unable to transform or replicate in other quail or chicken cells after exogenous infection, despite the fact that the viral particles contain normal envelope glycoproteins, internal structural proteins and RNA-dependent DNA polymerase. The lack of infectivity of 21Q1b virions is a consequence of the failure to package genomic 39S RNA. Instead, these virions contain a mixture of heterogenous-sized polyadenylated cellular RNAs and 4S RNA. Less than 1% of the encapsulated RNA is viral-specific, although in the 21Q1b-producing cells, amounts of 39S, 28S and 21S viral RNAs comparable to those in wild-type virus-infected cells are synthesized and function as mRNAs for the viral proteins. Thus 21Q1b can be considered an RNA packaging mutant. Superinfection of 21Q1b cells with either RAV-1 or PR-A leads to production of about 10% or more of the normal titer of superinfecting virus, but none of the 21Q1b genetic markers are rescued. After superinfection, the 21Q1b cells continue to synthesize 21Q1b particles containing cellular RNAs in the same amounts as before infection. Thus superinfection does not appear to "switch off" the aberrant packaging of cellular RNA, but allows packaging of the superinfecting RNA. One explanation for the phenotype of 21Q1b is that the genome is lacking a signal necessary for efficient genomic RNA packaging (but not for translation) and that the 21Q1b genome encodes a "packaging factor" with an altered specificity so that cellular RNAs are efficiently packaged. 21Q1b virions do contain RNA-dependent DNA polymerase which has normal endogenous synthetic activity. The cDNA product made in vitro from detergent-lysed 21Q1b virions hybridizes equally well to uninfected quail and 21Q1b-producing quail cell RNAs, with kinetics suggesting that the endogenous product consists of transcripts of cellular RNAs present in low amounts in the cells.
Cell 1978 Dec
PMID:An avian oncovirus mutant (SE 21Q1b) deficient in genomic RNA: biological and biochemical characterization. 8 99

Extracts from over 100 normal human placentas have been examined for RNA-directed DNA polymerase (DNA nucleotidyltransferase, EC 2.7.7.7) activity. More than 80% of these placentas contained this enzyme activity, which banded at a density of 1.15-1.17 g/ml in sucrose. After heat treatment, this enzyme activity was shifted in density to 1.22-1.24 g/ml. The enzymatic activity was greater with (rC)n.(dG)12-18 than with (dC)n.(dG)12-18 and was not stimulated by (dG)12-18 alone. The product of the endogenous reaction, which was sensitive to RNase, had the characteristics of a small DNA associated with a large RNA by hydrogen bonding. Electron microscopic inspection of the material with a density of 1.15-1.17 g/ml revealed numerous retrovirus-like particles with central electron-dense cores and double-membraned envelopes. The enzyme may be associated with the retrovirus-lik particles noted in the trophoblast layer of some human placentas.
Proc Natl Acad Sci U S A 1978 Dec
PMID:Normal human placentas contain RNA-directed DNA polymerase activity like that in viruses. 8 52

TTP gamma-benzylamidates are shown to act as competitive inhibitors of poly(dT) synthesis catalyzed by E. coli RNA-dependent DNA polymerase. The KM value for TTP as well as KI values for the gamma-analogues have been determined. TTP gamma-4-(N-2-chloroethyl-N-methyl-amino)benzylamidate is shown to be an effective affinity reagent for this enzyme.
Biokhimiia 1978 Dec
PMID:[Affinity alkylation of E. coli RNA-dependent DNA polymerase with TTP gamma-amidate derivatives]. 8 90

Conditions are described which give an efficient synthesis of DNA copies of cowpea mosaic virus (CPMV) RNAs, using avian myeloblastosis reverse transcriptase and oligo (dT) primers. Maximum incorporation of dAMP into cDNA is attained with 0.4 to 0.8 mM of each deoxynucleoside triphosphate, 12 mM Mg++ and 60 mM K+ ion concentrations. High enzyme concentrations (up to 100 units/ml) were used. Under these conditions over 1000 pmoles of dAMP were incorporated per reaction. The cDNA:RNA molar ratio approached 0.3 when 1 pmole CPMV RNA was used as template. The products were heterogeneous but large. Bottom component RNA (about 6000 nucleotides long) was copied into cDNA molecules ranging from about 1000 to 4000 nucleotides, and middle component RNA (about 4000 nucleotides long) was copied into cDNA mostly between 500 and 2000 nucleotides long, on average about 1500, which can be cleaved by restriction endonuclease Hae III into two fragments of 880 and 540 nucleotides.
Nucleic Acids Res 1978 Dec
PMID:Efficient reverse transcription of cowpea mosaic virus RNAs. 8 93

Relevant data pertaining to present evidence for virus-like particles and virus-related macromolecules in human milk and breast tumors are presented. A critical review and discussion of reported observations concerning virus-related macromolecules will include RNA-directed DNA polymerase, viral antigens, and RNA related to murine mammary tumor virus and/or Mason-Pfizer monkey virus. From the standpoint of clinical applications, the finding of viral-related antigens in human breast tumors and evidence for specific host immune responses to one or more of these antigens may be especially pertinent. The latter data, therefore, will be discussed in depth as to possible employment of these parameters in diagnosis, prognosis and possible management of the human disease.
CRC Crit Rev Clin Lab Sci 1979 Dec
PMID:Virus-like particles and macromolecules in human milk and breast tumors. 9 88

We have partially purified and characterized two separate DNA polymerase activities associated with Epstein-Barr virus (EB virus). One activity is present in EB virus producer cell lines but not in nonproducer or negative cell lines. It adheres more strongly to DEAE-cellulose than any host cell enzymes, eluting at 210 to 270 mM potassium phosphate buffer. Further elution from phosphocellulose and sedimentation in glycerol gradients yields an enzyme purified 900-fold with an S value of 8.3. The second DNA polymerase activity co-purifies with EB viral particles, elutes at low salt from DEAE-cellulose (40 to 60 mM potassium phosphate buffer) and phosphocellulose (100 mM), and has an S value of 9.5 on glycerol gradient sedimentation. These two enzymes are referred to for convenience as the EB virus-induced DNA polymerase and the EB virion-associated DNA polymerase. The EB virus-induced polymerase can be distinguished from host alpha, beta, and the virion-associated polymerase in 1) being resistant to salt inhibition, 2) having a more basic pH optima in Tris buffer (pH 9.5), and 3) having a 10-fold lower saturating concentration for the activated DNA template. The EB virion-associated polymerase is distinguished from host alpha, beta, and the EB virus-induced polymerase, because it cannot utilize synthetic deoxy- and ribohomopolymer primer-templates in place of the activated calf thymus DNA template in DNA polymerase assays. Neither of the EB virus-associated polymerases can copy the ribohomopolymers dT10poly(rA) or dG12-18(poly(rC) efficiently and therefore can be distinguished from host gamma polymerase and reverse transcriptase. The activity of the EB virus-induced and virion-associated polymerases are unaffected both by antibody to alpha polymerase, and by antiserum with high antibody titers to EB early antigen and viral capsid antigen.
J Biol Chem 1978 Dec 10
PMID:Two Epstein-Barr virus-associated DNA polymerase activities. 21 39


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