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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Many bovine leukemic lymphocytes produce virus particles when kept in survival cultures in Eagle's Minimum Essential Medium supplemented with 20 percent of inactivated fetal calf serum. Virus particles equilibrate at a density of 1.16 g/ml in sucrose gradients and at a density of 1.12 g/ml in metrizamide gradients. Simultaneous detection tests show that a high molecular weight RNA-reverse transcriptase complex exists in these viruses. Hybridizations between total RNA from bovine leukemic lymphocytes and C-DNA prepared in various known RNA oncogenic viruses show that the virus associated with bovine leukosis is unrelated to RLV, SSV-1, MSV-Ki, FSV-Ga and FLV-Ri.
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PMID:Biochemical approach to bovine leukemia. 5 80

Procedures were established for the isolation and partial purification of DNA polymerase, RNA polymerase and poly(A) polymerase activities from the cytoplasm and nuclei of NIH-Swiss mouse embryos. Based on the elution pattern of these enzyme activities from DEAE-cellulose and phosphocellulose columns in Tris-HCl buffer, pH 8.0, the apparent basicities of the enzymes can be arranged as follows: cytoplasmic(C) poly(A) polymerase greater than (C)DNA polymerase beta greater than (C)DNA polymerase alpha and nuclear(N) poly(A) polymerase greater than (N)DNA polymerase greater than (N)RNA polymerase I greater than (N)RNA polymerase II. Twenty rifamycins, including rifamycin B, rifamycin S, rifamycin SV, and rifamycin SV derivatives, were examined for their ability to inhibit the above mentioned nucleic acid polymerizing enzymes and Simian sarcoma virus type I (SSV-1) reverse transcriptase. Rifamycin SV 3'-formyldiphenylhydrazone, rifamycin SV 3'-formyl-n-octyloxime (AF/013) and rifamycin SV 3'-formyldiphenylmethyloxime (AF/05) inhibited all the tested enzyme activities. Rifamycin SV 3'-formylpropylphenyloxime (AF/015) inhibited cellular nucleic acid polymerase activities but not SSV-1 DNA polymerase activity. Rifamycin SV 3'-formyldinitrophenylhydrazone (AF/DNFL) strongly inhibited reverse transcriptase activity but did not inhibit cellular DNA polymerase activities. AF/DNFI slightly inhibited RNA and poly(A) polymerase activities. Rifamycin SV 3'-formyldipropylhydrazone (AF/DPI) and 2,6-dimethyl-4-N-benzyldemethyl-rifampicin (AF/ABDMP) slightly inhibited reverse transcriptase activity but did not inhibit cellular nucleic acid polymerase activities. Active rifamycin derivatives inhibited enzyme reactions by interacting with the enzyme proteins. Nascent polynucleotide chain elongation continued although at a reduced rate in the presence of inhibitor. The addition of increasing concentrations of nonionic detergent (Triton X-100) to rifamycin-inhibited enzyme reactions fully restored enzyme activities. The presence of highly lipophilic 3'-side chains on active rifamycins and the reversibility of enzyme inhibition by Triton X-100 suggest that the tested nucleic acid polymerizing enzymes may have hydrophobic regions with which inhibitory rifamycins interact.
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PMID:Interaction of rifamycins with mammalian nucleic acid polymerizing enzymes. 6 93

Short term cultures of bovine leukemic lymphocytes release virus particles with biochemical properties of RNA oncogenic viruses. These particles, tentatively called Bovine Leukemia Virus (BLV) have a high molecular weight-reverse transcriptase complex and a density averaging 1.155 g/ml in sucrose solutions. Molecular hybridizations between BLV-3H cDNA and several viral RNAs show that BLV is not related to Mason-Pfizer Monkey Virus (MPMV) Simian Sarcoma Associated Virus (SSV-1) Feline Leukemia Virus (FeLV) or Avian Myeloblastosis Virus (AMV). Rauscher Leukemia Virus (RLV) exhibits a slight but reproducible relatednesse to BLV. The high preference of BLV reverse transcriptase for Mg++ as the divalent cation suggests that BLV might be an atypical mammalian leukemogenic type C virus. Hybridization studies using BLV 3H cDNA as a probe suggest that the DNA of bovine leukemic cells contains viral sequences that cannot be detected in normal bovine DNA.
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PMID:Bovine leukemia virus: an exogenous RNA oncogenic virus? 6 82

A new retravirus (SMRV) isolated from a squirrel monkey, Saimiri sciureus, has an Mg2+-dependen reverse transcriptase and a buoyant density of 1.17 g/cm3 in sucrose and 1.21 g/cm3 in cesium chloride, similar to the mouse mammary tumor virus and the Mason-Pfizer monkey virus. The polypeptide patter of SMRV as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was distinct from the reported polypeptide patterns of known retraviruses. Four major polypeptides of molecular weights 40,000, 20,000, 14,000 and 8,000 were resolved in virus propagated in human, mink, and canine cells. In A204 human rhabdomyosarcoma cells, a protein of 73,000 daltons (gp73) represented the major viral glycoprotein as determined by [3H]glucosamine labeling. Additional proteins were also observed, but their presence depended on the cell type in which the virus was propagated. In both species-and interspecies-specific assays, no antigenic relatedness was observed between SMRV and Mason-Pfizer monkey virus, mouse mammary tumor virus, baboon endogenous virus (BaLV), woolly monkey virus (SSV-1), murine leukemia virus, endogenous feline type C virus (RD-114), bovine leukemia virus, and equine infectious anemia virus. These findings indicate that SMRV represents a new retravirus and the first isolate from a New World monkey.
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PMID:Characterization of a retravirus isolated from squirrel monkeys. 6 28

MRC-5 human diploid cells infected with Simian Sarcoma Virus from woolly monkey (SSV-1) were not transformed but an efficient replication of non transforming SiLV was demonstrated. Increase of virus reverse transcriptase activity paralleled cell replication during successive passages. Preliminary results concerning the influence of viral infection on the life span and the karyotype of MRC-5 diploid cells will be reported and several implications of these findings discussed.
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PMID:Replication of primate oncornavirus SSV-1 on MRC-5 human diploid cells. 7 83

Reverse transcriptase from foamy virus, strain H4188 was estimated and purified. The enzyme has the following characteristics: 1. The reaction utilized preferentially oligo (dT) poly (rA) as a primer-template; however, the synthetic primer-template oligo (dT) poly (dA) could also be used to some extent. 2. The reaction utilized oligo (dG) poly (rC) as a primer-template with very low efficiency. 3. The crude virus preparation had a detectable endogenous reaction using the four deoxyribonucleotides for DNA polymerization. 4. The cation requirement for the enzyme reaction was much more biased for Mn++ than for Mg++ ions. 5. The molecular weight of the partially-purified enzyme was estimated to be about 80,000. Aggregates of 240,000 daltons were also seen. The activity of this enzyme was not inhibited by antisera against the reverse transcriptases of various type C RNA viruses, namely, feline endogenous leukemia virus, RD 114, Woolly simian sarcoma virus (SSV-1) and avian myeloblastosis virus (AMV). Antiserum against Rauscher leukemia virus (RLV) enzyme was marginally active against foamy virus enzyme, perhaps indicating a slight cross-reaction. The biochemical characteristics of foamy virus reverse transcriptase seemed to be very close to those of the type C RNA viruses, but the immunological reaction proved that the foamy virus reverse transcriptase was distinct from the others.
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PMID:Reverse transcriptase of foamy virus. Purification of the enzymes and immunological identification. 7 44

Simian sarcoma virus, type 1 (SSV-1)-transformed non-producer cell lines were established by infection of normal marmoset fibroblast cells (HF) with limiting dilutions of SSV-1. Four focus-derived cell lines were identified as non-producers by assay of culture fluids for focus-forming activity and by the mixed culture cytopathogenicity test with XC cells. Further studies failed to detect production of type-C virus by 3H-uridine labelling, reverse transcriptase assay or electron microscopy. The non-producer cell lines, designated HF/SSV-NPI, IV, V, and VI, appeared morphologically transformed and cloned in soft agar with the same efficiency as HF/SSV-1 virus-producing transformed cells. Expression of either cytoplasmic or cell surface virus-related antigens was not detected by immunofluorescence or serum cytotoxicity tests. The presence of sarcoma genome in the transformed non-producer cell lines was demonstrated by rescue of focus-forming activity following superinfection with non-transforming helper virus or by cocultivation with helper-virus-producing cell lines. The SSV-1-transformed non-producer primate cells provide a useful tool for future studies.
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PMID:Establishment of simian sarcoma virus, type 1 (SSV-1)-transformed non-producer marmoset cell lines. 19 78

Enzymological properties of the RNA-directed DNA polymerase associated with the Suncus murinus mammary tumor virus (Sm-MTV) was investigated and its antigenic relatedness to other retroviral DNA polymerases was examined. The enzyme exhibited higher activity in the presence of Mg2+ than in the presence of Mn2+ with endogenous RNA as well as with almost all of the synthetic template X primers tested. Mg2+ was also effective with poly(2'-O-methylcytidylate) X oligodeoxyguanylate which was known to be specific for Mn2+. To examine the immunological relatedness of this enzyme with other retroviral DNA polymerases, remaining Sm-MTV DNA polymerase activity was measured after treatment of this enzyme with various antisera prepared against each of the reverse transcriptases of Mason-Pfizer monkey virus (MPMV), murine mammary tumor virus (MuMTV), simian sarcoma virus-simian sarcoma associated virus (SSV/SSAV), and Rauscher murine leukemia virus (RLV). No inhibition of the Sm-MTV enzyme activity was observed when treated with the latter three antisera with which the DNA polymerase activities of the corresponding retroviruses were fully inhibited. Only the antiserum against MPMV-enzyme, however, was found to slightly inhibit the Sm-MTV enzyme activity. These results indicate that Sm-MTV DNA polymerase has similar enzymological properties to those of MPMV and MuMTV and shares some common antigenic determinant group(s) with MPMV DNA polymerase.
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PMID:Biochemical and immunological characterization of Suncus murinus mammary tumor virus DNA polymerase. 241 16

Chronic myelogenous leukemia (CML) is a stem cell disease which, on a clinical level, progresses from the release from growth control of normally differentiated cells (a preleukemic state) to an acute leukemia. On a molecular level, the evolution of CML to acute leukemia is a multistep process. We propose that an early step, at the stem cell level, is acquisition of the ability for gene movement, which allows subsequent submicroscopic and chromosomal rearrangements that cause changes in the growth characteristics and regulation of the stem cell. A specific platelet DNA polymerase (PDP - reverse transcriptase) may play a role in gene movement. The characteristic reciprocal translocation of chromosomes #9 and #22, causing the activation of the c-abl oncogene, appears to be responsible for the uncontrolled cellular growth. Yet, other growth factors (e.g., platelet derived growth factor) and activated oncogenes (e.g., c-sis) must be responsible for the stimulation, progression, and variability seen during the course of the disease. Because CML is a progressive disease with clinically definable stages, CML appears to be a model system for the study of the molecular basis of the progression of preleukemia to leukemia specifically, and preneoplasia to aggressive neoplasia in general.
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PMID:Implications of retroviral and oncogene activity in chronic myelogenous leukemia. 243 4

Single-stranded complementary DNA (cDNA) of the RNA of Gazdar murine sarcoma virus, Gz-MSV/MuLV; Moloney murine leukemia virus, M-MuLV; mouse mammary tumor virus, MMTV; and simian sarcoma virus, SSV-1, were synthesized in endogenous reverse transcriptase reaction. Gz-MSV/MuLV cDNA was also synthesized in exogenous in vitro reverse transcriptase reactions. In the endogenous reaction, 30-35S, or 6.0- to 7.9-kilobase-length cDNA transcripts were synthesized in high yield. In comparison, transcripts synthesized in exogenous reactions were 6.7S, or 0.39 kilobases. The complementarity of the transcripts was verified by both RNA/DNA hybridization and protection studies. dG and dC sequences were detected in 50-77% of the cDNA molecules by affinity chromatography, by annealing and masking studies, and by resistance to S1 nuclease. dT and dA sequences were not detected in the transcripts. These findings are discussed in relation to the possible selective blocking of transcription of retrovirus genes without interfering significantly with the transcription of cellular genes.
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PMID:Complementary DNA copies of leukemia and sarcoma virus RNA contain sequences of deoxycytidylate and deoxyguanylate. 629 64


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