Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By equilibrium dialysis a disadenosine 5',5'''-P1,P2-tetraphosphate (Ap4A) binding activity is shown to be present in mammalian cells. The Ap4A binding activity copurifies with DNA polymerase alpha during the isolation procedure, which includes chromatography on phospho-, DEAE-, and DNA-cellulose; gel filtration; sucrose gradient centrifugation; and electrophoresis in nondenaturing polyacrylamide gels. After these purification steps, DNA polymerase alpha appears to be homogeneous in nondenaturing polyacrylamide gels. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis of such a purified DNA polymerase alpha preparation reveals seven distinct protein bands with apparent Mrs of 64,000, 63,000, 62,000, 60,000, 57,000, 55,000, and 52,000. By affinity labeling, the protein with Mr 57,000 has been shown to be the Ap4A-binding constituent of DNA polymerase alpha. The binding activity of DNA polymerase alpha for Ap4A is highly specific because neither structural analogs nor several other adenine nucleotides compete effectively with Ap4A for its binding site. The Ap4A binding site is lost in neuronal cells during maturation of rat brains concomitantly with the loss of DNA polymerase alpha and mitotic activity in those cells. From these results, DNA polymerase seems to be the intracellular target of Ap4A. This is discussed in respect to the recently reported of Ap4A to trigger DNA replication in quiescent mammalian cells [Grummt, F. (1978) Proc. Natl. Acad. Sci. USA 75, 371-375].
 ...
PMID:Diadenosine 5',5'''-P1,P4-tetraphosphate, a ligand of the 57-kilodalton subunit of DNA polymerase alpha. 29 4

A single peak of DNA polymerase activity was detectable by phosphocellulose chromatography of leukemic guinea pig lymphoblast whole cell extracts. The inability to detect multiple peaks of activity as described with other cell types is shown to be due to the insolubility of a large proportion of the DNA polymerase activity under the extraction condition used. Multiple forms of DNA polymerase with different template specificities were recognized in extracts of the subcellular fractions of these cells after chromatography on phosphocellulose and DEAE cellulose. On Sephadex G-200 gel filtration these enzymes had apparent molecular weights in excess of 140,000 daltons. No RNA polymerase (reverse transcriptase) was detected in any subcellular fraction despite the presence of oncornavirus like particles in these cells.
 ...
PMID:Studies of the template preference and other characteristics of the DNA polymerases of leukemic guinea pig lymphoblasts. 29

Two DNA polymerases are present in extracts of commercial bakers' yeast and wild type Saccharomyces cerevisiae grown aerobically to late log phase. Yeast DNA polymerase I and yeast DNA polymerase II can be separated by DEAE-cellulose, hydroxylapatite, and denatured DNA-cellulose chromatography from the postmitochondrial supernatants of yeast lysates. The yeast polymerases are both of high molecular weight (greater than 100,000) but are clearly separate species by the lack of immunological cross-reactivity. Analysis of associated enzyme activities and other reaction properties of yeast DNA polymerases provides additional evidence for distinguishing the two species. Enzyme I has no associated nuclease activity but does carry out pyrophosphate exchange and pyrophosphorolysis reactions, and has an associated 3'-exonuclease activity. Enzyme I does not degrade deoxynucleoside triphosphates and cannot utilize a mismatched template. Enzyme II does carry out a template-dependent deoxynucleoside triphosphate degradation reaction and can excise mismatched 3'-nucleotides from suitable template systems. Earlier studies have shown that both Enzyme I and Enzyme II are inhibited by N-ethylmaleimide. The yeast enzymes are not identical to any known eukaryotic or prokaryotic DNA polymerases. In general, Enzyme I appears to be most similar to eukaryotic DNA polymerase alpha and Ezyme II exhibits properties of prokaryotic DNA polymerases II and III.
 ...
PMID:DNA polymerases from bakers' yeast. 32 47

RNA-linked DNA fragments of T7-infected Escherichiacoli were labeled with [(32)P]orthophosphate invivo. The RNA segments of the labeled fragments were isolated by degrading the DNA portion with the 3'--> 5' exonuclease intrinsic to bacteriophage T4 DNA polymerase and fractionated according to net charge by a DEAE-Sephadex A-25 column chromatography in the presence of 7 M urea. Tri-, tetra- and pentanucleotides were obtained which have ATP residues at their 5' ends. Most of the pentanucleotides had a single deoxynucleotide at the 3' end but a minor portion was totally an oligoribonucleotide. In the light of prior results, the former is a cooligomer of an intact tetraribonucleotide primer and a monodeoxynucleotide and the latter is an intact pentaribonucleotide primer. Tri- and tetraribonucleotides with ATP at the 5' ends had no deoxynucleotide at the 3' ends, therefore it is not clear if intact triribonucleotide primers are present. The 5'-terminal dinucleotides of the tetra- and pentanucleotides were mostly pppApC and a trace amount of pppApA was present.Images
 ...
PMID:RNA-linked nascent DNA pieces in phage T7-infected Escherichia coli. III. Detection of intact primer RNA. 38 59

Two different DNA polymerases have been purified and characterized from human platelets. In the mitochondrial fraction a unique activity of the polymerase gamma type has been found. The same enzyme is found in the extramitochondrial supernatant. A second DNA polymerase, called 'cytoplasmic' DNA polymerase has been found in the 10000 x g supernatant of human platelets. The following properties of the latter DNA polymerase from human platelets are identical to those of DNA polymerase alpha from normal cells: DEAE-cellulose and phosphocellulose chromatography, size, thermal stability, phosphonoacetic acid and ethidium bromide inhibition. However, some of its properties, like high resistance to N-ethylmaleimide and the lack of DNA polymerization using synthetic RNA primers, are those of DNA polymerase beta.
 ...
PMID:DNA polymerases of anucleated cells. Isolation and characterization of two DNA polymerases from human platelets. 42 79

Aqueous extracts of isolated nuclei and intact plasmodia of Physarum contain a heat-stable stimulator of nuclear DNA replication. The stimulatory factor is present throughout the mitotic cycle, and its activity is unaffected by prior exposure of plasmodia to cycloheximide. The stimulatory substance has been partially purified by heat treatment, precipitation with ethanol, chromatography on DEAE cellulose, and gel filtration. The purified material contains both carbohydrate and protein, and exhibits a molecular weight of about 30 000. The active substance increases the rate and overall extent of DNA replication in S-phase nuclei, but does not trigger the initiation of DNA synthesis in nuclei isolated from G2-phase plasmodia. The stimulatory material contains little or no deoxyribonuclease or DNA polymerase activity, and it does not affect DNA polymerase activity assayed using a purified DNA template.
 ...
PMID:Isolation of a stimulatory factor for nuclear DNA replication. 53 38

Two forms of DNA polymerase alpha were separated from HeLa cells by DEAE-cellulose column chromatography and affinity chromatography using a DNA-cellulose column. They were eluted from a DEAE-cellulose column at 0.22M KCl (P-I) and 0.24M KCl (P-II). Upon cell fractionation between cytosol and nuclei, P-I was recovered from nuclei and P-II from cytosol. P-I was found to have a higher binding affinity to DNA than P-II by DNA-cellulose column chromatography.
 ...
PMID:Separation of two forms of HeLa DNA polymerase alpha with different binding affinity to DNA. 55 47

The level of DNA polymerase gamma as compared to DNA polymerases alpha and beta has been determined in chick embryo by means of specific tests: the amount of gamma-polymerase in the 12-day-old chick embryo reaches about 15% of the total polymerase activity. This enzyme is mainly localized in nuclei and mitochondria, where it represents the prevailing if not the unique DNA polymerase activity. The mitochondrial DNA polymerase gamma is likely to be associated with the internal membrane or the matrix of this organelle since it is not removed by digitonin treatment. The gamma-polymerases have been purified from chick embryo nuclei and mitochondria 500-700 times by means of DEAE-cellulose, phosphocellulose and hydroxyapatite chromatographies. The purified mitochondrial DNA polymerase gamma is closely related to the homologous enzyme purified from the nuclei of the same cells. So far, they cannot be distinguished on the basis of their sedimentation, catalytical properties and response to inhibitors or denaturating agents. The purified gamma enzymes are distinct from the chick embryo DNA polymerases alpha and beta and are not inhibited by antibodies prepared against the latter enzymes. The nuclear and mitochondrial gamma-polymerases do not respond to the oncogenic RNA virus DNA polymerase assay with natural mRNAs.
 ...
PMID:Chick-embryo DNA polymerase gamma. Identity of gamma-polymerases purified from nuclei and mitochondria. 56 88

DNA polymerase was purified 1000-fold from the cytoplasm of microplasmodia of the myxomycete Physarum polycephalum. The activity was found in two forms exhibiting molecular weights of 204000 and 116000 respectively. Both forms eluted together from DNA-cellulose and DEAE-Sephadex columns. The Stokes radii were 6.5 and 5.5 nm. The sedimentation coefficients were 7.6 and 5.2 S. The frictional ratios of 1.69 suggest a highly hydrated and/or an asymmetric structure of the molecule. The enzyme-catalyzed reaction was sensitive to N-ethylmaleimide (60% inhibition by 1 mM). Unlike DNA polymerase alpha from mammalian cells the Physarum enzyme was stimulated by 30 mM NaCl. Activated DNA was the preferred template. Poly(A) . (DT)12 was not accepted. The Km value for deoxynucleoside triphosphates was 3 micron, for activated DNA 50 microgram/ml and for Mg2+ at the optimum [k+] of 150 mM about 0.6 mM.
 ...
PMID:Deoxyribonucleic acid polymerase from Physarum polycephalum. Properties of the major cytoplasmic activity in exponentially growing microplasmodia. 56 99

DNA polymerase alpha and beta were identified in the urchin, Strongylocentrotus purpuratus. The DNA polymerase beta sedimented at 3.4 S, constituted 5% of total DNA polymerase activity, and was resistant to N-ethylmaleimide and high ionic strength. The polymerase alpha sedimented at 6--8 S, was inhibited by N-ethylmalemide or 0.1 M (NH4)2SO4, and was dependent upon glycerol for preservation of activity. Both the polymerases alpha and beta were nuclear associated in embryos. The DNA polymerase alpha was markedly heterogeneous on DEAE-Sephadex ion exchange and showed three modal polymerase species. These polymerase alpha species were indistinguishable by template activity assays but the DNA polymerase associated ribonucleotidyl transferase (Biochemistry 75 : 3106-3113, 1976) was found predominantly with only one of the DNA polymerase alpha species.
 ...
PMID:DNA polymerase alpha and beta in the California urchin. 56 91


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>