Reprogramming cellular events by poly(ADP-ribose)-binding proteins Abstract Poly(ADP-ribosyl)ation is a posttranslational modification catalyzed by the poly(ADPribose) polymerases (PARPs). These enzymes covalently modify glutamic, aspartic and lysine amino acid side chains of acceptor proteins by the sequential addition of ADP-ribose (ADPr) units. The poly(ADP-ribose) (pADPr) polymers formed alter the