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)

Nuclear protein factor type 1 (NPF-1) that simulates IMR-32 primase-associated DNA polymerase alpha 1 and alpha 2 activities has been purified from a high-salt extract of liver chromatin from 6-month-old rats. The final purified factor lacks DNA polymerase alpha, RNA polymerase, and DNA-unwinding or topoisomerase type I activities. The stimulatory activity is destroyed by trypsin (60 min at 37 degrees C), DNase II (60 min at 37 degrees C), and heat treatment (2 min at 68 degrees C). The 125I-labeled NPF-1 does not bind to activated calf thymus DNA or poly(dC). However, it forms a ternary complex with DNA in the presence of DNA polymerase alpha-primase complex (alpha 1 and alpha 2). The ternary complex sediments on sucrose density gradient as a heavier band (11S). The NPF-1 also stimulates (2.5-fold) primase-catalyzed incorporation of GMP and dGMP from the corresponding triphosphates on poly(dC) template even in the presence of a high concentration of alpha-amanitin (400 micrograms/ml). The labeled duplex containing the poly(dC) template, [32P]-GTP, and [3H]dGTP loses 80% of the 32P label and 70% of the 3H label after treatment with 0.3 M KOH and DNase I, respectively. The products were isolated from reaction mixtures incubated with and without NPF-1 and subjected to alkaline sucrose-density-gradient sedimentation analysis. The results suggest that the rate of synthesis of DNA short chains is increased in the presence of NPF-1 without a concomitant increase in the chain length of the newly synthesized products.
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PMID:Stimulation of human neuroblastoma DNA polymerase alpha and primase activities by a protein factor isolated from rat liver chromatin. 354 Sep 37

One of the two forms of DNA polymerase alpha from ovaries of the frog Xenopus laevis catalyzed ribonucleoside triphosphate-dependent DNA synthesis on single-stranded circular fd phage DNA templates. DNA synthesis was dependent on ATP and added template. CTP, GTP, and UTP stimulated DNA synthesis but were not required and could not substitute for ATP. DNA synthesis was not inhibited by alpha-amanitin. Neither poly(dT) nor double-stranded DNA served as template. Analysis of [32P]-dTMP-labeled product by neutral and alkaline agarose gel electrophoresis showed that 0.1- to 1-kilobase DNA fragments (average size of approximately equal to 0.25 kilobase) were synthesized. The fragments were not covalently linked to the template. Either [alpha-32P]NMP, [gamma-32P]ATP, or [gamma-32P]GTP were incorporated also into the product. Analysis of the product after hydrolysis by KOH, alkaline phosphatase, or bacteriophage T4 3' leads to 5' exonuclease showed the presence of a small oligoribonucleotide primer at the 5' end of the newly synthesized DNA. NTP-dependent DNA-synthesizing activity copurified on six columns and cosedimented during glycerol gradient centrifugation with one form of DNA polymerase alpha activity but not with the other form. These results suggest that DNA primase activity is associated with one of the two forms of X. laevis DNA polymerase alpha.
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PMID:DNA primase activity associated with DNA polymerase alpha from Xenopus laevis ovaries. 696 3