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)

The addition of iododeoxyuridine to P3HR-I cell cultures led to a large increase in both Epstein-Barr virus (EBV)-induced DNA polymerase activity and early antigen-positive cells. This EBV-induced DNA polymerase was separated from the cellular alpha- and beta-polymerases by sequential column chromatography on Sepharose 6B, DEAE-cellulose, and phosphocellulose, resulting in partial purification of about 320-fold. The partially purified-EBV DNA polymerase could be distinguished from the cellular DNA polymerases by its activation by salts, its catalytic properties, and its degree of sensitivity to N-ethylmaleimide, phosphonoacetic acid, araATP, and araCTP. The viral polymerase showed properteis similar to those reported for other herpesvirus DNA polymerases. The enzyme exhibited optimal activity for copying activated calf DNA in the presence of 50 mH (NH4)2SO4 and was resistant to 150 mM (NH4)2SO4. It utilized with high efficiency template-primer poly(dC)-oligo(dG)12-18 or poly(dA)-oligo(dT)12-18, but failed to copy poly(rA)-oligo(dT)10 and oligo(dT)10, indicating that this enzyme has characters distinct from DNA polymerase gamma, reverse transcriptase, and terminal deoxynucleotidyl transferase. Phosphonacetic acid inhibited not only EBV DNA polymerase, but also, to a lesser degree, the cellular polymerase alpha. AraATP did not severely inhibit viral activity, whereas the polymerase alpha was inhibited most effectively. Both EBV polymerase and polymerase alpha were inhibited at a comparable level by araCTP.
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PMID:Characterization of an Epstein-Barr virus-induced DNA polymerase. 21 9

A complex which is active in in vitro synthesis of adeno-associated virus (AAV) DNA was solubilized from Vero cells that were co-infected with AAV and either adenovirus (Ad5) or a herpes simplex virus type 1 (HSV-1) as the helper virus. The complexes from the Ad5 and HSV-1-infected cells sedimented at 23 S and 28 S, respectively. The optimal conditions for in vitro DNA synthesis for the two types of complex using the endogenous AAV template and the endogenous DNA polymerase, differed with respect to the effect of KCl and K2SO4 concentration. In addition the complex from HSV-1-infected cells, but not that from Ad5-infected cells, was inhibited by phosphonoacetic acid. Thus, the two complexes appear to contain different DNA polymerase activities. This was verified by phosphocellulose chromatography of the DNA polymerases solubilized from the isolated complexes. The major activity in the complex from HSV-1 infected cells was the HSV-induced DNA polymerase with lesser amounts of cellular DNA polymerase alpha and gamma or both. The complex from the Ad5-infected cells contained mainly a cellular DNA polymerase gamma.
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PMID:Adeno-associated virus DNA replication complexes in herpes simplex virus or adenovirus-infected cells. 22 4

Specificity of TdT5 as a marker for ALL was evaluated by determining its activity in cells from normal control subjects and from 35 pediatric patients with ALL, AML, Hodgkin's disease and disseminated Burkitt's lymphoma. We evaluated the DNA polymerase activity, cell surface phenotypes (E rosettes, EAC rosettes, Smlg and la-like, HTLA and cALL antigens), and hematological and cytochemical characteristics in both the normal and patient groups. DNA polymerase alpha + beta and DNA polymerase gamma activity were indiscriminately high in all immature cells as found in ALL, AML, Burkitt's lymphoma and phytohemagglutinin-stimulated normal lymphocytes, when compared to mature leukocytes found in normal individuals or in patients whose cancer was in remission. High TdT activity was found in 24 of 26 T and non-T/non-B ALL patients in active phase as well as in two of three AML patients one of whom had Auer rods. Thus, TdT, although valuable for monitoring ALL patients, may have limitations in separating AML from ALL.
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PMID:High terminal deoxynucleotidyl transferase activity in pediatric patients with acute lymphocytic and acute myelocytic leukemias. 27 33

The physiological functions of DNA polymerases (deoxynucleosidetriphosphate:DNA deoxynucleotidyltransferase, EC 2.7.7.7) beta and gamma were investigated by using neuronal nuclei and synaptosomes isolated from rat brain. UV irradiation of neuronal nuclei from 60-day-old rats resulted in a 7- to 10-fold stimulation of DNA repair synthesis attributable to DNA polymerase beta which, at this developmental stage, is virtually the only DNA polymerase present in the nuclei. No repair synthesis could be elicited by treating the nuclei with N-methyl-N-nitrosourea, but this way probably due to the inability of brain tissues to excise alkylated bases from DNA. The role of DNA polymerase gamma was studied in synaptosomes by using a system mimicking in vivo mitochondrial DNA synthesis. By showing that, under these conditions, DNA replication occurs in mitochondria, and exploiting the fact that DNA polymerase gama is the only DNA polymerase present in mitochondria, evidence was obtained for a role of DNA polymerase gamma in mitochondrial DNA replication. Based on these results and on the wealth of literature on DNA polymerase alpha, we conclude that DNA polymerase alpha is mainly responsible for DNA replication in nuclei, DNA polymerase beta is involved in nuclear DNA repair, and DNA polymerase gamma is the mitochondrial replicating enzyme. However, minor roles for DNA polymerase alpha in DNA repair or for DNA polymerase beta in DNA replication cannot be excluded.
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PMID:Functional roles of DNA polymerases beta and gamma. 28 74

The effects of the inhibitors 2'3' dideoxythymidine triphosphate (ddTTP) and 1-beta-D-arabinofuranosyl cytosine triphosphate (araCTP) on DNA synthesis in isolated S-phase HeLa S3 nuclei have been examined. These effects are compared with the effects of the same inhibitors in partially purified preparations of DNA polymerases alpha and beta. The effect of ddTTP on partially purified DNA polymerase gamma was also tested. DNA polymerases beta and gamma were very sensitive to ddTTP whereas DNA polymerase alpha and DNA synthesis in isolated nuclei were quite resistant. The synthesis and subsequent ligation of primary DNA pieces ('Okazaki fragments') were not affected by the presence of this inhibitor. DNA synthesis in isolated nuclei and DNA polymerase alpha activity were very sensitive to araCTP whereas DNA polymerase beta was almost totally resistant to the inhibitor. The results indicate a major role for DNA polymerase alpha in DNA replication.
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PMID:The role of DNA polymerases alpha, beta and gamma in nuclear DNA synthesis. 43

An adenovirus (Ad) DNA replication complex extracted from infected HeLa nuclei could be purified free of the bulk of intracellular DNA polymerase activity by sedimetation in neutral sucrose gradients. However, the replication complex still retained some alpha and gamma DNA-polymerase activity. Since this complex is inhibited by 2', 3' dideoxythymidine-5'-triphosphate (ddTTP), an inhibitor of DNA polymerase gamma, a functional role for this enzyme in Ad DNA replication is suggested. Similar inhibition by ddTTP in intact Ad infected nuclei and comparable inhibition of Ad DNA synthesis in whole cells by dideoxythymidine (ddThy) are consistent with a role for DNA polymerase gamma. Uninfected HeLa nuclei or whole cells are not similarly inhibited by ddTTP or DDThy respectively. Such data does not rule out an additional functional role for other DNA polymerases, and recent experiments from this laboratory (1) suggest that DNA polymerase alpha is also involved in Ad DNA synthesis.
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PMID:The DNA polymerases associated with the adenovirus type 2 replication complex: effect of 2'-3'-dideoxythymidine-5'-triphosphate on viral DNA synthesis. 44 Sep 66

Poly(dT) products which were synthesized depending on (rA)n . (dT)12-18 as a template . primer by mammalian DNA polymerases beta and gamma were analyzed by alkaline sucrose gradient centrifugation. The size of the population of poly(dT) chains synthesized by DNA polymerase beta increased slowly and consistently during incubation up to at least 30 min. On the other hand, the product size with DNA polymerase gamma reached the final size (7 s) within 5 min and the number of products increased during further incubation. Comparison of product number per enzyme molecule suggests that DNA polymerase beta acts on multiple primers in a distributive fashion while DNA polymerase gamma completes poly(dT) chains of large size in a one-by-one fashion.
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PMID:Difference in the mechanisms of poly(dT) synthesis by DNA polymerases beta and gamma. 45 49

DNA polymerase beta was isolated from rat cortex neurons and characterised. Its properties were strikingly similar to those of other mammalian beta-polymerases. In adult rats, this was the major DNA polymerase occurring in neuronal nuclei, which contained no alpha-polymerase, 99.2% beta-polymerase and only 0.8% gamma-polymerase. Isolated neuronal nuclei of this developmental stage were shown to perform ultraviolet-induced repair DNA synthesis in vitro. Since beta-polymerase was virtually the exclusive DNA polymerase in these nuclei it was concluded that the beta enzyme was responsible for the observed DNA repair. This was further substantiated by demonstrating a virtually complete suppression of DNA repair in irradiated nuclei by 2',3'-dideoxyribosylthymine 5'-triphosphate (d2TTP), a potent beta-polymerase inhibitor. However, the presence of minute amounts of gamma-polymerase in neuronal nuclei and its susceptibility to d2TTP did not allow one to rule out an ancillary role of DNA polymerase gamma in DNA repair. In view of the similarity of the neuronal DNA polymerase beta with all other mammalian beta-polymerases it may be speculated that the ability to perform repair DNA synthesis is not unique to the neuronal enzyme but is a general function of all beta-polymerases.
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PMID:DNA polymerase beta from brain neurons is a repair enzyme. 46 24

The optimal condition for the rat DNA polymerase beta activity with (rA)n . (dT)12-18 as a template-primer was determined. The activity was remarkably affected by the concentration of the primer, (dT)12-18' and the mixing ratio of (dT)12-18 to (rA)n. DNA polymerase beta requires higher primer concentration (Km = 11.1 microM with respect to 3'-OH of the primer) than DNA polymerase gamma (Km = 0.04 microM) or oncornaviral DNA polymerase (Km = 0.08 microM) and the enzyme represented the maximum activity in the base ratio of 2:1 with (dT)12-18 and (rA)n suggesting the difference in reaction mechanisms of these enzymes. Under the optimized conditions, the specific activity of the near homogeneous preparation of DNA polymerase beta was 1,000,000 units per mg protein.
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PMID:Unique requirements for template primers of DNA polymerase beta from rat ascites hepatoma AH130 cells. 50 43

The activities of DNA polymerases alpha, beta, and gamma and of thymidine kinase were determined in the chick neural retina at different stages of embryonic development (starting at seven days) and after hatching (up to five years). Crude extracts of neural retinae were fractionated by centrifugation on sucrose gradients and the enzymatic activities measured using specific assays. The DNA polymerase alpha activity decreases greatly between 7 and 11 days of incubation. This decrease parallels the decline in mitotic activity. However, a constant residual activity remains after hatching, even in the oldest animals. DNA polymerase beta activity increases slightly between 7 and 14 days of incubation; it then decreases slowly until seven days after hatching and remains constant thereafter. DNA polymerase gamma activity is maximal between 7 and 14 days of incubation and then decreases until hatching. The activity of thymidine kinase increases slightly during the embryonic life until hatching and remains almost constant thereafter. The implication of these enzymes in DNA replication and repair processes is discussed.
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PMID:Variation of DNA polymerase activities in chick neural retina as a function of age. 52 76


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