, Volume 138, Issue 1-2, pp 39-44

Interaction of poly(ADP-ribose)polymerase with DNA polymerase α

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Homogeneously purified poly(ADP-ribose) polymerase (PARP) specifically stimulated the activity of immunoaffinity-purified calf or human DNA polymerase α by about 6 to 60-fold. Apparently, poly(ADP-ribosyl)ation of DNA polymerase α was not necessary for the stimulation. The effects of PARP on DNA polymerase α were biphasic: at very low concentrations of DNA, it rather inhibited its activity, whereas, at higher DNA concentrations, PARP greatly stimulated it. The autopoly(ADP-ribosyl)ation of PARP suppressed both its stimulatory and inhibitory effects. By immunoprecipitation with an anti-DNA polymerase α antibody, it was clearly shown that PARP may be physically associated with DNA polymerase α. Stimulation of DNA polymerase α may be attributed to the physical association between the two, rather than to the DNA-binding capacity of PARP, since the PARP fragment containing only the DNA binding domain showed little stimulatory activity. The existence of PARP-DNA polymerase α complexes were also detected in crude extracts of calf thymus.