DNA polymerase activities in differentiating mouse neuroblastoma N-18 cells

Proc Natl Acad Sci U S A. 1978 Mar;75(3):1289-93. doi: 10.1073/pnas.75.3.1289.


The activities of two DNA polymerases (DNA nucleotidyltransferases) were characterized in mouse neuroblastoma clone N-18 on the basis of their apparent molecular weights (determined by sucrose density gradient centrifugation: polymerase-alpha, 7.5-8 S; polymerase-beta, 3-4 S) and relative inhibition by sulfhydryl-blocking agents. N-Ethylmaleimide (10 mM) and iodoacetamide (1.5 mM) inhibited DNA polymerase-alpha activity completely, whereas only 35-40% inhibition was observed for DNA polymerase-beta under similar conditions. DNA polymerase-alpha activity was reduced 50-70% in N-18 cells that had been induced to differentiate by 4 micro M bromodeoxyuridine, and the low molecular weight DNA polymerase-beta activity remain unchanged. With activated calf thymus DNA as template, only DNA polymerase-alpha activity was stimulated in the presence of added ribonucleotides and purified Escherichia coli RNA polymerase.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bromodeoxyuridine / pharmacology*
  • Cell Differentiation / drug effects*
  • Cell Line
  • DNA Polymerase I / antagonists & inhibitors
  • DNA Polymerase I / metabolism*
  • DNA Polymerase II / antagonists & inhibitors
  • DNA Polymerase II / metabolism*
  • DNA, Neoplasm / biosynthesis
  • DNA-Directed DNA Polymerase / metabolism*
  • DNA-Directed RNA Polymerases / metabolism
  • Neoplasms, Experimental
  • Neuroblastoma / enzymology*
  • Sulfhydryl Reagents / pharmacology


  • DNA, Neoplasm
  • Sulfhydryl Reagents
  • DNA-Directed RNA Polymerases
  • DNA Polymerase I
  • DNA Polymerase II
  • DNA-Directed DNA Polymerase
  • Bromodeoxyuridine