ABSTRACT
Poly(ADP-ribose) polymerase (PARP) is a major nuclear protein associated with chromatin that contains zinc fingers and binds to either double-or single-strand DNA breaks. PARP is activated upon binding to DNA and forms covalent homopolymers of poly(ADP-ribose) (PAR) attached to a number of nuclear proteins, including itself and proteins involved in DNA replication, DNA repair, and apoptosis. Nuclear NAD, which comprises 95% of the total cellular NAD, is the substrate for polymer formation. PARP has been implicated in numerous biological functions involved with the breaking and rejoining of DNA.
