A new mammalian DNA polymerase with 3' to 5' exonuclease activity: DNA polymerase delta.
A new species of DNA polymerase has been purified more than 10 000-fold from the cytoplasm of erythroid hyperplastic bone marrow. This DNA polymerase, in contrast to previously described eukaryotic DNA polymerases, is associated with a very active 3' to 5' exonuclease activity. Similar to the 3' to 5' exonuclease activity associated with prokaryotic DNA polymerases, this enzyme catalyzes the removal of 3'-terminal nucleotides from DNA, as well as a template-dependent conversion of deoxyribonucleoside triphosphates to monophosphates. The exonuclease activity is not separable from the DNA polymerase activity by chromatography on DEAE-Sephadex or hydroxylapatite, and upon sucrose density gradient centrifugation the two activities cosediment at 7 S or at 11 S depending on the ionic strength. Both exonuclease and polymerase activities have identical rates of heat inactivation and both are equally sensitive to hemin and Rifamycin AF/013, inhibitors of DNA synthesis that act by binding to DNA polymerase and causing its dissociation from its template/primer. These results are consistent with the coexistence of two enzyme activities in a single protein.
D001853:Bone Marrow / Q000201:enzymology*; D004254:DNA Nucleotidyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D004355:Drug Stability; D004900:Erythroblasts / Q000201:enzymology*; D004912:Erythrocytes / Q000201:enzymology*; D005092:Exonucleases / Q000302:isolation & purification / Q000378:metabolism*; D006427:Hemin / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D013696:Temperature
D006427:Hemin; D004254:DNA Nucleotidyltransferases; D005092:Exonucleases