Further characterization of a poly(rA) . oligo(dT)-dependent activity of multiple DNA polymerase alpha from calf thymus

Biochim Biophys Acta. 1981 Jul 27;654(2):194-200. doi: 10.1016/0005-2787(81)90172-6.


DNA polymerase alpha (EC from calf thymus has been separated into three molecular species, i.e., 10 S DNA polymerase alpha, 6.5 S DNA polymerase alpha-1 and 6.5 S DNA polymerase alpha-2 (Masaki, S. and Yoshida, S. (1978) Biochim, Biophys. Acta 531, 74-88; Yoshida, S., Yamada, M., Masaki S. and Seneyoshi, M. (1979) Cancer Res. 39, 3955-3958). Among these three, 10 S DNA polymerase alpha and 6.5 S DNA polymerase alpha-2 were found to copy efficiently poly(rA) . oligo(dT), a template-primer, which was thought to be specific for DNA polymerase gamma or beta. 6.5 S DNA polymerase alpha-1, however, could not use the ribopolymer as a template. The poly(rA) . oligo(dT)-dependent activities of DNA polymerase alpha species differed markedly from those with activated calf thymus DNA in sensitivity to various reagents: the former was inhibited more than 80% by 80 mM KCl, while the latter was stimulated somewhat. Furthermore, aphidicolin, a specific inhibitor of DNA polymerase alpha, did not inhibit the poly(rA) . oligo(dT)-dependent activity. 2',3'-DideoxyTTP, a potent inhibitor of DNA polymerase beta or gamma, slightly inhibited the reactions with poly(rA) . oligo(dT), while it did not inhibit the reactions with activated DNA. The apparent Km values for dTTP on poly(rA) . oligo(dT) template were 260 and 70 microM for 10 S alpha and 6.5 S alpha-2, respectively; these values were much higher than those obtained on activated DNA template (8-10 microM).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • DNA Polymerase II / antagonists & inhibitors
  • DNA Polymerase II / metabolism*
  • DNA-Directed DNA Polymerase / metabolism*
  • Dideoxynucleotides
  • Kinetics
  • Oligodeoxyribonucleotides / pharmacology*
  • Oligonucleotides / pharmacology*
  • Poly A / pharmacology*
  • Potassium Chloride / pharmacology
  • Substrate Specificity
  • Thymine Nucleotides
  • Thymus Gland / enzymology*


  • Dideoxynucleotides
  • Oligodeoxyribonucleotides
  • Oligonucleotides
  • Thymine Nucleotides
  • Poly A
  • poly(rA).oligo(dT)
  • Potassium Chloride
  • DNA Polymerase II
  • DNA-Directed DNA Polymerase
  • 2',3'-dideoxythymidine triphosphate