title: Differential inhibition of multiple forms of DNA polymerase alpha from IMR-32 human neuroblastoma cells.
abstract: Three forms of DNA polymerase (pol) alpha from human neuroblastoma IMR-32 were separated by DEAE column chromatography. All sedimented at approximately 7 S in 5-20% continuous sucrose density gradients. All were heat labile, with pol alpha 2 the most (90% inactivated) and pol alpha 3 the least (50% inactivated) sensitive to heating for 5 min at 50 degrees C. pol alpha 1 and alpha 2 efficiently utilized activated calf thymus DNA as template. The most active form, pol alpha 2, used both poly(dA).(dT)12-18 and poly(dT).(dA)12-18 as template at equal rates. Differential inhibition of DNA polymerase alpha activities was examined in the presence of ricin, hemin, and a nonhistone chromatin protein. All three polymerases were inhibited by both ricin (nonreduced) and hemin, with pol alpha 2 the most (80-90%) and pol alpha 3 the least (60%) sensitive in each case. In contrast, only pol alpha 2 and alpha 3 activities were inhibited (80-85%) by rat liver nonhistone chromatin protein.
mesh_terms: D000818:Animals; D002413:Cations, Divalent; D002460:Cell Line; D002868:Chromosomal Proteins, Non-Histone / Q000302:isolation & purification; D004257:DNA Polymerase II / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D007700:Kinetics; D037102:Lectins / Q000494:pharmacology; D008099:Liver / Q000032:analysis; D009447:Neuroblastoma / Q000201:enzymology*; D019384:Nucleic Acid Synthesis Inhibitors; D011089:Polydeoxyribonucleotides; D051381:Rats; D013698:Templates, Genetic; D014118:Toxins, Biological / Q000494:pharmacology
chemical_list: D002413:Cations, Divalent; D002868:Chromosomal Proteins, Non-Histone; D007527:Isoenzymes; D037102:Lectins; D019384:Nucleic Acid Synthesis Inhibitors; D011089:Polydeoxyribonucleotides; D014118:Toxins, Biological; D004257:DNA Polymerase II