title: Structural homology among calf thymus alpha-polymerase polypeptides.
abstract: A sample of highly purified calf thymus alpha-polymerase contained an abundant 118,000 Mr polypeptide as well as five lower molecular weight polypeptides in the range of 54,000- to 64,000-Mr. This 118,000-Mr polypeptide was capable of DNA polymerase activity, as revealed by in situ assay after SDS-polyacrylamide gel electrophoresis. Tryptic peptide mapping indicated that the 118,000-Mr polypeptide shared extensive primary structure homology with 57,000-, 58,000- and 64,000-Mr polypeptides and some limited homology with 54,000- and 56,000-Mr polypeptides. This is the first evidence that lower and higher Mr polypeptides of purified calf thymus alpha-polymerase share sequence homology; these results are interpreted in the context of a model that predicts the existence of a common precursor with molecular weight greater than 140,000.
mesh_terms: D000818:Animals; D002417:Cattle; D004257:DNA Polymerase II / Q000302:isolation & purification; D004259:DNA-Directed DNA Polymerase / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D046911:Macromolecular Substances; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D013950:Thymus Gland / Q000201:enzymology*; D014357:Trypsin
chemical_list: D046911:Macromolecular Substances; D010446:Peptide Fragments; D004257:DNA Polymerase II; D004259:DNA-Directed DNA Polymerase; D014357:Trypsin