Mode of inhibition of DNA synthesis induced by adenosine diphosphoribosylation of nuclear protein

DNA obtained after complete removal of the proteins from NAD-treated rat liver chromatin possessed template capacity equivalent to that obtained from untreated chromatin. The stepwise extraction of proteins from chromatin affected a gradual removal of labeled ADPR and a parallel decrease of the inhibition. The results of the present study suggest that the inhibition of the template capacity for DNA synthesis following preincubation of chromatin with NAD is dependent upon ADP-ribosylation of the associated proteins. The template capacity of chromatin and nucleoprotein complex (Weiss preparation) for DNA synthesis was inhibited, whereas the capacity for RNA synthesis was apparently not affected.