Probable involvement of a glycoconjugate in IMR-32 DNA synthesis: decrease of DNA polymerase alpha 2 activity after tunicamycin treatment

Proc Natl Acad Sci U S A. 1982 Mar;79(5):1488-91. doi: 10.1073/pnas.79.5.1488.


Multiple forms of DNA polymerase alpha activity (alpha 1, alpha 2, and alpha 3) from human neuroblastoma IMR-32 cells untreated or treated with tunicamycin (3 microgram/ml) were separated by DEAE-cellulose column chromatography. Loss of 40--60% of DNA polymerase alpha 2 activity was observed in tunicamycin-treated cells. Ricin 1B, a subunit of intact ricin (Mr, 64,000), was found to be a specific inhibitor of DNA polymerase alpha 2 isolated from control IMR-32 cells. However, DNA polymerase alpha 2 isolated from tunicamycin-treated cells was insensitive to ricin 1B. Heat treatment studies at 50 degrees C showed two completely different inactivation profiles for the DNA polymerase alpha 2 enzymes isolated from the tunicamycin-treated and untreated cells. A probable involvement of a beta-linked galactose-containing carbohydrate chain in the catalytic subunit of DNA polymerase alpha 2 is suggested.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cells, Cultured
  • DNA Replication / drug effects*
  • Glucosamine / analogs & derivatives*
  • Glycoproteins / metabolism
  • Hot Temperature
  • Humans
  • Kinetics
  • Nucleic Acid Synthesis Inhibitors*
  • Ricin / pharmacology
  • Templates, Genetic
  • Tunicamycin / pharmacology*


  • Glycoproteins
  • Nucleic Acid Synthesis Inhibitors
  • Tunicamycin
  • Ricin
  • Glucosamine