Mono ADP-ribosylation and poly ADP-ribosylation of proteins in normal and malignant tissues.

Three subclasses of (ADPR)n protein conjugates were quantified from intact tissue; proteins carrying poly(ADPR) and two types of mono(ADPR) protein conjugates, one susceptible, the other resistant to neutral hydroxylamine. Mono(ADPR) conjugates were found in all major compartments of the liver cell although the two subfractions were unevenly distributed. Poly(ADPR) protein conjugates appear to be restricted to the nucleus. Independent changes of the subclasses in normal and malignant tissues associated with cell growth and differentiation also point to independent functions. Hydroxylamine-resistant mono(ADPR) protein conjugates of various tissues changed with the degree of terminal differentiation. Formation of poly(ADPR) proteins, on the other hand, was stimulated by treatment of cells with alkylating agents which lead to DNA-fragmentation. This points to an involvement of polyADP-ribosylation in DNA excision repair.