Structural study of immunoaffinity-purified DNA polymerase alpha-DNA primase complex from calf thymus

Biochim Biophys Acta. 1988 Sep 7;950(3):263-73. doi: 10.1016/0167-4781(88)90122-4.


The DNA polymerase alpha-DNA primase complex was purified over 17,000-fold to near homogeneity from calf thymus using an immunoaffinity column. Sodium dodecyl sulfate gel electrophoresis revealed three polypeptides with molecular weights of 140, 50 and 47 kDa, in a ratio of 1:2:0.25. The complex showed a sedimentation coefficient of 9.7 S, a Stokes radius of 56 A and a native molecular weight of 250-260 kDa. Taken together, the data suggest that the calf thymus dNA polymerase alpha-DNA primase complex is essentially a heterotrimer of large (140 kDa) and small (50 kDa) subunits in a ratio of 1:2, with a globular conformation. Electron-microscopic studies of the complex revealed a spherical particle of 120 A in diameter, in agreement with the physiochemical results. The binding of the complex to DNA was also demonstrated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • Chromatography, Affinity
  • DNA Primase
  • Macromolecular Substances
  • Microscopy, Electron
  • Molecular Weight
  • Protein Conformation
  • RNA Nucleotidyltransferases / isolation & purification*
  • RNA Nucleotidyltransferases / metabolism
  • Thymus Gland / enzymology*


  • Macromolecular Substances
  • DNA Primase
  • RNA Nucleotidyltransferases