PARP4, also known as vPARP, is the largest member of the poly-ADP-ribose polymerase (PARP) family. PARP4 exhibits PARP activity and can PARylate major vault protein (MVP) and, to a lesser extent, itself. Vaults are the largest ribonucleoprotein particles found in eukaryotic cells [].Poly(ADP-ribosyl)ation (PARylation) is a post-translational modification of proteins []. PARP family members are PAR polymerases that initiate the reaction by converting the substrate nicotinamide adenine dinucleotide (NAD+) to ADP-ribose, and then catalyse ADP-ribose polymerisation on nuclear acceptor proteins [].
