Abstract
In a recent study we have reported the utilization of exogenous NAD by the tegumental membrane which does not appear to involve a typical ADP-ribose (ADPR) transferase system. The incorporation of tritiated material from the NAD precursor into an acid-insoluble fraction was not inhibited by 3-acetamidobenzamide which is a potent competitive inhibitor of all nuclear ADPR transferases. The system was, however, sensitive to the calmodulin antagonist trifluoperazine. Extending these investigations, we report that NAD degradation occurs through a sequence of intermediates before incorporation as a purine-containing metabolite which is insoluble in trichloroacetic acid.