Regulation of poly(ADP-ribose) transferase activity by 2',5'-oligoadenylates.

pppA2'pA2'pA appears to be a potent natural noncompetitive inhibitor of poly (ADP-ribose) transferase activity in the histone dependent reaction of ADP-ribosylation with Ki=5 microM. Moreover, it is a noncompetitive inhibitor of the Mg2+ dependent reaction of autoADPRT-ribosylation with Ki=20 microM. The activity of ADPRT falls down abruptly both in the cytoplasm and nuclei of mouse L-cells treated with interferon. In contrast, the activities of 2',5'-oligo (A) polymerase and 2'-phosphodiesterase remain virtually unchanged after the treatment with ADPRT preparation. The regulation of ADPRT activity and active form of ADPRT by 2',5-oligoadenylates is presumed to be one of the factors responsible for inducing the antiviral and/or antiproliferative effects of interferon.