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)

An antigen crossreacting with the 30,000-molecular-weight protein (p30) of the feline endogenous oncornavirus (RD114) was detected in a well-characterized human fibrosarcoma cell line, HT1080, by indirect immunofluorescence. Three antisera against RD114 p30 gave similar positive results, while two antisera prepared against simian sarcoma virus p30, one antiserum prepared against murine leukemia virus p30, and one antiserum prepared against feline leukemia virus p30 gave no immunofluorescence. The reactivity observed with the antiserum against RD114 p30 was detected in 10-40% of the cells at early passages and was no longer expressed by the forty-first subculture. The reactivity could be removed by adsorption of the antiserum with RD114-infected dog or human cells, but not by uninfected cells or by cells infected with an antigenically unrelated oncornavirus, feline leukemia virus. Neither complete virus particles nor reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) activity was detected in the culture. These experiments suggest that the fibrosarcoma cell line is expressing an antigen related to the p30 protein of RD114 baboon endogenous virus group of oncornaviruses without producing complete virions.
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PMID:Expression of antigenic crossreactivity to RD114 p 30 protein in a human fibrosarcoma cell line. 6 79

The purpose of this investigation was to search for oncornavirus in primary cell cultures obtained from leukemic cattle organs and lymphocytes and to study their molecular-biological properties and role in the etiology of cattle leukemia. The investigation was carried out on 25 primary trypsinized cell culutres of lymph nodes, spleens, kidneys and lymphocytes from cattle with acute and chronic leukemia. It was demonstrated that all cell cultures from leukemic cattle (in contrast to cell cultures from healthy cattle) released oncornavirus into the culture medium. The virus possesses the main properties of oncornaviruses: it has a virion of C-type structure with a density of 1.16--1.18g/ml in a 20--60 per cent sucrose gradient, which may be induced by 5-bromodeoxyuridine, inhibited by Actino-mycin D, has reverse transcriptase activity, contains 60S RNA, that is annealed in the reaction of molecular hybridization with DNA of lymph nodes of cattle with leukemia. The propagation of the isolated oncornavirus in continuous cell lines of calf kidney culture was demonstrated. Experimental inoculation of purified oncornavirus was carried out on 60 baby calves and 15 lambs from leukosis free herds or flocks. Several of the calves later showed evidence of virus infection.
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PMID:Isolation and characterisation of oncornavirus from primary cultures of tissues from cattle with leukemia. 6 13

Sera from some leukemic cattle contain an antibody that inhibits the reverse transcriptase activity of the bovine leukemia virus. The antibody is not directed against the synthetic template or the major internal and envelope viral antigens. The antibody failed to inhibit the DNA polymerases of the murine leukemia virus, simian sarcoma-associated virus, avian myeloblastosis virus, or Escherichia coli. Conversely, the bovine leukemia virus enzyme was not inhibited by antibody against the reverse transcriptases of other C-type viruses. These findings agree with previous results showing that the major internal bovine leukemia virus protein lacks the known interspecies- and intraspecies-specific antigenic determinants indentified in the homologous proteins of other oncornaviruses.
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PMID:Inhibition of the reverse transcriptase of bovine leukemia virus by antibody in sera from leukemic cattle and immunological characterization of the enzyme. 6 83

Northern poke lymphosarcoma DNA polymerase was partially purified from particulate fractions banding at 1.15 to 1.16 g/ml from homogenates prepared from frozen necropsies of tumor-bearing pike. The enzyme behaves as a typical reverse transcriptase, in that it prefers ribotemplates to deoxytemplates. The isoelectric point (pl 5.5) is similar to that of avian myeloblastosis virus polymerase. The pike enzyme elutes from a phosphocellulose column at 0.22 M potassium phosphate, the same as avian myeloblastosis virus DNA polymerase. The enzyme activity is inhibited by pyran, a specific inhibitor of viral DNA polymerases. The most striking difference between the pike lymphoma polymerase and the other viral DNA polymerases tested is the low maximum temperature of 20 degrees, compared to 30 degrees for Rauscher leukemia virus polymerase and 38 degrees for avian myeloblastosis virus and Rous sarcoma virus.
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PMID:Presence of DNA polymerase in lymphosarcoma in northern pike (Esox lucius). 6 92

The reverse transcriptase was purified to homogeneity from Rauscher leukemia virus by sequential column chromatography on phosphocellulose and DNA-cellulose. The purified enzyme, a single polypeptide chain with a molecular weight of approximately 70,000, interacts with major internal protein p30 of the same virus. The reverse transcriptase - p30 complex stimulated [3H]TMP incorporation into (dT)12 - (rA)n 2- to 3-fold compared to that observed with the purified enzyme alone. Monospecific antiserum made against either p30 or reverse transcriptase precipitated the entire complex. The sedimentation rate of the reverse transcriptase - p30 complex is approximately 12 S as estimated by glycerol gradient centrifugation, and the molecular weight is approximately 400,000 by chromatography on a Sepharose 6B column. The complex dissociates into its original components when treated with 0.8 M KCl.
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PMID:Effect of Rauscher leukemia virus-specific proteins on reverse transcriptase. Binding between reverse transcriptase and p30. 6 27

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

A type C RNA virus has been detected in the culture fluids of the SU-DHL-1 human histiocytic lymphoma cell line previously established in this laboratory. In electron micrographs, the virus closely resembled other typical mammalian type C RNA tumor viruses in size and morphology. Viral RNA-dependent DNA polymerase activity has been demonstrated in particles (densities of 1.15 and 1.22 g/ml) in the microsomal cytoplasmic fraction and in pellets of culture fluids. The enzyme is partially inhibited by antibodies to the RNA-dependent DNA polymerases of simian sarcoma virus and RD-114 virus but not by antibody to the polymerase of murine leukemia virus, suggesting some degree of relatedness to type C viruses of subhuman primate origin. Typical syncytial microplaques were induced when SU-DHL-1 cells were cocultivated with rat XC cells. Although no focus formation was noted in similarly cocultivated mouse UC1-B cell cultures, the numbers of foci induced in rat embryo fibroblasts by murine sarcoma virus were significantly increased by coinfection with the virus from SU-DHL-1 cell culture fluids. No other evidence of infectivity, inducibility, or capacity for helper rescue of defective murine sarcoma virus genomes has been detected to date in cocultivation studies with a spectrum of fibroblastic and other nonlymphoid indicator cell lines of human and other species of origin.
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PMID:Isolation of a type C RNA virus from an established human histiocytic lymphoma cell line. 7 39

Similarities have been observed for some time between oncornavirus-induced malignancies in laboratory animals and leukemias and solid tumors in man. Particles similar to type C oncornaviruses have been detected by electron microscopy both in cells or plasma from leukemia patients and in solid-tumor human malignancies such as Hodgkin's lymphoma, lymphosarcomas, and sarcomas. Likewise, particles resembling type B oncornaviruses in shape and appearance have been found in human breast cancer. In neither case has the infectious nature of the particles been confirmed. However, DNA synthesized in vitro by the enzyme of murine mammary tumor virus was found to hybridize with polysomal RNA obtained from human mammary adenocarcinomas. The presence of RNA complementary to RNA from the Rauscher strain of murine leukemia virus has been observed in other human malignancies unrelated to breast cancer. It has also been found that cells of patients with myelogenous leukemia possess an oncornaviral-type reverse transcriptase that is distinguishable from other cell DNA polymerases and serologically related to the reverse transcriptase of primate oncornaviruses.
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PMID:Human studies following animal models of tumorigenesis by oncornaviruses. 7 Nov 81

A high molecular weight RNA-reverse transcriptase complex in the culture media of peripheral leukocytes obtained from two Japanese patients with myeloma-leukemia was detected by demonstration of a 3H-uridine peak and a peak of DNA polymerizing activity banding at a density of 1.15-1.19g/ml. The enzyme in the complex was able to utilize poly(rA)-d(pT)10 or poly (rC)-d(pG) 12-18, but not poly (dA)-d(pT) 10 or (dT) 12-18 as template-primers. The sucrose density sedimentation analysis revealed that RNA in the complex sedimented at a location of approximately 50s and 20-30s.
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PMID:RNA-reverse transcriptase complex from cultured human myeloma-leukemia cells. 7 Dec 70

Human ribonucleases were purified from the sera of Hodgkin's disease patients by sequential column chromatography. The purified enzyme interacted with reverse transcriptase of Rauscher leukemia virus and formed an additive complex of Mr = 130,000. RNase and oligo(dG)-directed reverse transcriptase activities were diminished in the complex. The complex could be dissociated with the subsequent restoration of both activities in the presence of spermidine. The molecular weight of the complex suggest that the 2 RNase molecules bind to a single reverse transcriptase molecule.
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PMID:Complexing Rauscher leukemia virus reverse transcriptase with human plasma ribonuclease from Hodgkin's disease patients. 7 69


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