title: Probable involvement of a glycoconjugate in IMR-32 DNA synthesis: decrease of DNA polymerase alpha 2 activity after tunicamycin treatment.
abstract: 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.
mesh_terms: D002478:Cells, Cultured; D004261:DNA Replication / Q000187:drug effects*; D005944:Glucosamine / Q000031:analogs & derivatives*; D006023:Glycoproteins / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D019384:Nucleic Acid Synthesis Inhibitors; D012276:Ricin / Q000494:pharmacology; D013698:Templates, Genetic; D014415:Tunicamycin / Q000494:pharmacology*
chemical_list: D006023:Glycoproteins; D019384:Nucleic Acid Synthesis Inhibitors; D014415:Tunicamycin; D012276:Ricin; D005944:Glucosamine