title: DNA polymerase gamma from Xenopus laevis. II. A 3'----5' exonuclease is tightly associated with the DNA polymerase activity.
abstract: Xenopus laevis DNA polymerase gamma co-purifies with a tightly associated 3'----5' exonuclease. The purified enzyme lacks 5'----3' exonuclease and endonuclease activity. The ratio of the 3'----5' exonuclease activity to DNA polymerase gamma activity remains constant over the final three chromatographic procedures. In addition, these activities co-sediment under partially denaturing conditions in the presence of ethylene glycol. The associated 3'----5' exonuclease activity removes a terminally mismatched nucleotide more rapidly than a correctly base-paired 3'-terminal residue, as expected if this exonuclease has a proofreading function. The 3'----5' exonuclease has the ability to release a terminal phosphorothioated nucleotide, a property shared with T4 DNA polymerase, but not with Escherichia coli DNA polymerase I.
authors.affiliation: Department of Pharmacological Sciences, State University of New York, Stony Brook 11794-8651.
authors.forename: N F
authors.initials: NF
authors.lastname: Insdorf
authors.forename: D F
authors.initials: DF
authors.lastname: Bogenhagen
mesh_terms: D000818:Animals; D001483:Base Sequence; D004258:DNA Polymerase III / Q000302:isolation & purification / Q000378:metabolism*; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009838:Oligodeoxyribonucleotides; D009865:Oocytes / Q000201:enzymology*; D011489:Protein Denaturation; D013379:Substrate Specificity; D014982:Xenopus laevis
chemical_list: D009838:Oligodeoxyribonucleotides; D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V