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:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An RNA-directed DNA polymerase was found to be associated with intracytoplasmic A-particles from DBA/2 mouse leukemia cells. The enzyme activity was detected after disrupting the purified particles with 2 M NaCl-20 mM dithiothreitol. The presence of a divalent cation and all four deoxyribonucleoside triphosphates was essential for this enzyme activity. The enzyme had a clear preference for Mg2+ over Mn2+. Cesium sulfate isopycnic gradient centrifugation of the DNA product synthesized in the actinomycin D-containing reaction revealed the presence of DNA-RNA hybrid. Furthermore, the purified DNA product was found to hybridize with RNA isolated from A-particles. These observations strongly indicate that the endogenous A-particle RNA serves as the template for the DNA polymerase.
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PMID:Characterization of an RNA-directed DNA polymerase found in association with murine intracytoplasmic A-particles. 6 24

A marker rescue assay of noninfectious fragments of avian leukosis virus DNAs is describe. DNA fragments were prepared either by sonication of EcoRI-digestion of DNAs of chicken cells infected with wild-type Rous sarcoma virus, with a nontransforming avian leukosis virus, and with a mutant of Rous sarcoma virus temperature sensitive for transformation. Recipient cultures of chicken embryo fibroblasts were treated with noninfectious DNA fragments and infected with temperature-sensitive mutants of Rous sarcoma virus defective in DNA polymerase or in an internal virion structural protein. Wild-type progeny viruses which replicated at the nonpermissive temperature were isolated. Some of the wild-type progeny acquired both the wild-type DNA polymerase and the subgroup specificity of the Rous sarcona virus strain used for preparation of sonicated or EcoRI-digested DNA fragments. Therefore the genetic markers for DNA polymerase and envelope were linked and appeared to be located on the same EcoRi fragment of the DNA of Rous sarcoma virus-infected cells.
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PMID:Assay of noninfectious fragments of DNA of avian leukosis virus-infected cells by marker rescue. 6 25

In vitro synthesis of Rous sarcoma virus DNA by the virion endogenous DNA polymerase activity is initiated on a tRNAtrp primer located near the 5' end of the genome. A major product of such synthesis is a piece of DNA 101 nucleotides long (strong stop DNA) which can be isolated covalently bound to the tRNA primer. Here we show that the strong stop DNA is complementary to the extreme 5' end of the genome. We also show that the 5' and 3' termini of the Rous sarcoma virus genome, excluding the cap and the poly(A), have the identical sequence. We propose that the function of this sequence is to facilitate elongation from the 3' end of DNA chains initiated elsewhere on the virus genome.
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PMID:Terminal redundancy and the origin of replication of Rous sarcoma virus RNA. 6 72

We have previously reported [(Ohno, T., Sweet, R.W., Hu, R., DeJak, D. & Spiegelman, S. (1977) Proc. Natl. Acad. Sci. USA 74, 764-768)] on the purification and characterization of the DNA polymerase from human breast cancer particles. Its preference for certain synthetic templates and its ability to use a viral RNA to fashion a faithful DNA transcript identify it as a reverse transcriptase similar to that found in the mouse mammary tumor virus and in the Mason-Pfizer monkey virus (MPMV). We report here that the human breast cancer enzyme crossreacts immunologically with the reverse transcriptase of MPMV. The crossreactivity was shown both by inhibition of enzyme activity and by complex formation between purified enzyme and isolated IgG against MPMV polymerase. No such interactions were observed with other oncornavirus reverse transcriptases of avian, murine, feline, or simian origin. Further, the IgG failed to neutralize the reverse transcriptases from human mesenchymal neoplasias (leukemias and lymphomas) or the activities of normal cellular DNA polymerases (alpha, beta, gamma).
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PMID:Antigenic relatedness of the DNA polymerase of human breast cancer particles to the enzyme of the Mason-Pfizer monkey virus. 6 75

The cytoplasmic extracts of human prostatic tissues yield two classes of "particles" when centrifuged to equilibrium in a sucrose density gradient, one class banding at a density of 1.15-1.18 g/cm3 ("high density particles") and another at a density of 1.07-1.14 g/cm3 ("low density particles"). Both bands display endogenous DNA polymerase activity which is largely resistant to actinomycin D inhibition. The endogenous DNA products synthesized by high density particles give some indication of high molecular weight RNA:DNA complexes. The tissue extracts from normal, hyperplastic, and neoplastic prostate behave similarly in these assays. In addition, explant cultures of hyperplastic and neoplastic prostate either release, or can be induced to release, particles by treatment with bromodeoxyuridine. These particles band at a density of 1.15-1.18 g/cm3 in a sucrose density gradient and possess RNA and associated DNA polymerase activity which utilizes poly(A):oligo(dT). Our results suggest that human prostatic tissues may contain functions analogous in some ways to those of known RNA tumor viruses of other species.
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PMID:RNA tumor virus-like activities in human prostate: possible novel pharmacologic approaches. 6 16

An antiserum has been prepared against a highly purified DNA polymerase gamma from NC37 cells, a normal human lymphoblast cell line. The antiserum does not possess enzyme neutralizing activity, but does bind specifically to DNA polymerase gamma. When tested in a double antibody immunoprecipitation assay, the antibody does not cross-react with DNA polymerases alpha or beta, purified from NC37 cells, or with reverse transcriptases of avian, murine, or primate RNA tumor viruses. Antisera prepared against purified reverse transcriptases similarly do not recognize DNA polymerase gamma, either in an enzyme neutralization assay or in the more sensitive double antibody immunoprecipitation assay. The availability of an antiserum to DNA polymerase gamma will allow the further characterization of enzyme activities isolated from cellular material and suspected of being related to viral reverse ttranscriptases. In those cases where such activities do not immunologically resemble known viral DNA polymerases, the anti-DNA polymerase gamma will help determine the viral or cellular nature of the unknown activity.
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PMID:Serological analysis of cellular and viral DNA polymerases by an antiserum to DNA polymerase gamma of human lymphoblasts. 6 38

The effect of phenethyl alcohol on DNA synthesis was examined using several in vitro systems of Escherichia coli H560; i.e., ether-treated cells, membrane fractions and folded chromosomes fortified with DNA polymerase. In all systems, the incorporation of deoxyribonucleotides was much reduced for the phenethyl alcohol-treated cells compared with the non-treated cells. The total activity of DNA polymerases in polA1 cells (mostly DNA polymerase II) was not impaired for the phenethyl alcohol-treated cells and the reduction of the rate of DNA synthesis in vitro was ascribed to the reduction of the chromosomal template activity which was related to trypsin sensitive protein components. The analysis of chromosomes from the phenethyl alcohol-treated cells revealed the remarkable reduction of a protein component of molecular weight approx. 58 000 in contrast with a protein component of molecular weight approx. 30 000.
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PMID:The effect of phenethyl alcohol on in vitro DNA synthesis in Escherichia coli. 6 42

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

Squirrel monkey retrovirus (SMRV) was isolated by cocultivation of squirrel monkey lung cells with canine cells. 3H-labeled 60-70S SMRV RNA, isolated from virus grown in canine cells, hybridized to the same extent and to the same Cot1/2 value to the DNA of all tissues of all squirrel monkeys tested; Cot1/2 values show that SMRV proviral sequences are present in the low repetitive range. No SMRV proviral sequences were detected in tissues from a variety of other New World monkeys, Old World monkeys, or apes. Murine, feline, bovine, and canine cells also contain no detectable SMRV proviral sequences. Competitive molecular hybridization studies revealed no detectable sequence homology between the 60-70S RNAs of SMRV and Mason-Pfizer virus (MPV). The virion-associated DNA polymerase of SMRV is similar to that of MPV in that it has a molecular weight of approximately 80,000 and prefers magnesium as a divalent cation using oligo(dG)-poly(rC) as primer-template. The virion-associated DNA polymerase of SMRV can be clearly distinguished from those of MPV and the mouse mammary tumor viruses, however, by its preference for manganese as a divalent cation in the presence of high salt.
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PMID:Squirrel monkey retrovirus: an endogenous virus of a new world primate. 6 24

The circular DNA of hepatitis B Dane particles, which serves as the primer/template for an endogenous DNA polymerase, was analyzed by electrophoresis before and after a polymerase reaction and after digestion by restriction endonuclease or single-strand-specific endonuclease S1. The unreacted molecules extracted from the particles were electrophoretically heterogeneous, and treatment with S1 nuclease produced double-stranded linear DNA ranging in length from 1,700 to 2,800 base pairs (bp). After an endogenous DNA polymerase reaction, two discrete species of DNA molecules were found: a circular form and a linear form 3,200 bp long. The reaction resulted in a population of molecules with an elongated and more homogeneous double-stranded region. These results suggest that the circular molecules in Dane particles have single-stranded regions of varying lengths that are made double stranded during the DNA polymerase reaction. The endogenous DNA polymerase was found to initiate apparently at random in a region spanning more than a third of the molecule. Analysis of restriction endonuclease cleavage fragments of the fully elongated DNA revealed that although the molecules were of a uniform length, they were somewhat heterogeneous in sequence. The sum of the sizes of the 10 major endonuclease Hae III-generated fragments, detected by ethidium bromide, was 3,880 bp. Two additional fragments (B and G) detected by autoradiography after an endogenous DNA polymerase reaction with (32)P-labeled deoxynucleoside triphosphates made the total 4,910 bp.
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PMID:Structure of hepatitis B Dane particle DNA and nature of the endogenous DNA polymerase reaction. 6 27


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