Structural homology among calf thymus alpha-polymerase polypeptides

Nucleic Acids Res. 1982 Feb 11;10(3):935-46. doi: 10.1093/nar/10.3.935.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • DNA Polymerase II* / isolation & purification
  • DNA-Directed DNA Polymerase* / isolation & purification
  • Electrophoresis, Polyacrylamide Gel
  • Macromolecular Substances
  • Molecular Weight
  • Peptide Fragments / analysis
  • Thymus Gland / enzymology*
  • Trypsin


  • Macromolecular Substances
  • Peptide Fragments
  • DNA Polymerase II
  • DNA-Directed DNA Polymerase
  • Trypsin