PARP (Poly(ADP-Ribose) polymerase)

Poly(ADP-ribose) polymerase (PARP) is a 116 kDa stress response protein that repairs damaged DNA and regulates chromatin structure by poly(ADP-ribosyl)ation of nuclear proteins. Proteolytic cleavage of PARP into 89 kDA and 24 kDa fragments by caspases is an early indicator of apoptosis. Recent studies of PARP inhibitors have found that the inhibitors can prevent necrosis but not apoptosis in cells induced to die.