Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a key role in DNA repair.Mediates glutamate, aspartate or serine ADP-ribosylation of proteins: the ADP-D-ribosyl group of NAD+ is transferred to the acceptor carboxyl group of target residues and further ADP-ribosyl groups are transferred to the 2-position of the terminal adenosine moiety, building up a polymer with an average chain length of 20-30 units.
