WGR domain of poly(ADP-ribose) polymerase 1 and similar proteins
The WGR domain is found in a variety of eukaryotic poly(ADP-ribose) polymerases (PARPs). It has been called WGR after the most conserved central motif of the domain. The domain typically occurs together with a catalytic PARP domain, and is between 70 and 80 residues in length. It has been proposed to function as a nucleic acid binding domain. PARPs catalyze the NAD(+)-dependent synthesis of ADP-ribose polymers and their addition to various nuclear proteins. Higher eukaryotes contain several PARPs and and there may be up to 17 human PARP-like proteins, with three of them (PARP-1, PARP-2, and PARP-3) containing a WGR domain. The synthesis of poly-ADP-ribose requires multiple enzymatic activities for initiation, trans-ADP-ribosylation, elongation, branching, and release of the polymer from the enzyme. This subfamily is composed of vertebrate PARP-1 and similar proteins, including Arabidopsis thaliana PARP-1 and PARP-3. PARP-1 is the best-studied among the PARPs. It is a widely expressed nuclear chromatin-associated enzyme that possesses auto-mono-ADP-ribosylation (initiation), elongation, and branching activities. PARP-1 is implicated in DNA damage and cell death pathways and is important in maintaining genomic stability and regulating cell proliferation, differentiation, neuronal function, inflammation, and aging.