Nucleic Acids Research, 1982, Vol. 10, No. 3 935-946
© 1982
ENZYMOLOGY |
Structural homology among calf thymus 
-polymerase polypeptides+
1Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health Bethesda, MD 20205, USA 2Institut für Biochemie D-87 Wurzburg, FRG 3Institut für Pharmakologie and Biochemie, Med.-Vet. Fakultät der Universität Zürich Zürich, Switzerland
Received October 22, 1981. Revised December 17, 1981. Accepted December 17, 1981.
A sample of highly purified calf thymus 
-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 -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 >140,000.
+ This work was supported in part by a grant from the Deutsche Forschungsge-melnschaft to F.G.