ABSTRACT
The implication of poly (ADP-ribose) polymerase in DNA replication arises from observations where its enzymatic activity was found to be higher in proliferating cells than in quiescent cells. Poly (ADP-ribose) polymerase roles for both include the maintenance of chromatin superstructure, regulation of DNA Replication and DNA repair, cell multiplication, transformation, and differentiation. Considerable evidence has been accumulated showing that poly ADP-ribose is distributed in both histones and nonhistone proteins. The availability of a very sensitive radioactive assay for poly (ADP-ribose) polymerase and the success in the purification of this enzyme, has aided the elucidation of its association with chromatin and its possible role in the modulation of chromatin structure and function. This has been achieved by the reconstitution of the polymerase with chromatin, studies on the poly (ADP-ribose) polymerase-dependent nucleosomal aggregation, and the development of specific antibodies to this nonhistone protein. Histone H1 and core histones are major acceptors of poly (ADP-ribose) among this class of nuclear proteins.
