Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a key role in DNA repair (PubMed:10364231, PubMed:25043379, PubMed:27471034, PubMed:32028527, PubMed:32939087). 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 (PubMed:25043379, PubMed:30321391). Serine ADP-ribosylation of proteins constitutes the primary form of ADP-ribosylation of proteins in response to DNA damage (PubMed:32939087). Mediates glutamate and aspartate ADP-ribosylation of target proteins in absence of HPF1 (PubMed:25043379). Following interaction with HPF1, catalyzes serine ADP-ribosylation of target proteins; HPF1 conferring serine specificity by completing the PARP2 active site (PubMed:28190768, PubMed:32028527). PARP2 initiates the repair of double-strand DNA breaks: recognizes and binds DNA breaks within chromatin and recruits HPF1, licensing serine ADP-ribosylation of target proteins, such as histones, thereby promoting decompaction of chromatin and the recruitment of repair factors leading to the reparation of DNA strand breaks (PubMed:10364231, PubMed:32939087). In addition to proteins, also able to ADP-ribosylate DNA: preferentially acts on 5'-terminal phosphates at DNA strand breaks termini in nicked duplex (PubMed:27471034). NAD(+) + (ADP-D-ribosyl)n-acceptor = nicotinamide + (ADP-D-ribosyl)n+1-acceptor + H(+). L-seryl-[protein] + NAD(+) = H(+) + nicotinamide + O-(ADP-D-ribosyl)-L-seryl-[protein] L-aspartyl-[protein] + NAD(+) = 4-O-(ADP-D-ribosyl)-L-aspartyl-[protein] + nicotinamide L-glutamyl-[protein] + NAD(+) = 5-O-(ADP-D-ribosyl)-L-glutamyl-[protein] + nicotinamide Component of a base excision repair (BER) complex, containing at least XRCC1, PARP1, POLB and LRIG3 (By similarity). Homo- and heterodimer with PARP1 (PubMed:20092359). Interacts (via the PARP catalytic domain) with HPF1 (PubMed:27067600, PubMed:28190768, PubMed:32028527, PubMed:32939087, PubMed:33141820). Interacts with core nucleosomes (PubMed:32939087, PubMed:33141820). Recruited to DNA damage sites. Widely expressed, mainly in actively dividing tissues (PubMed:10364231). The highest levels are in the brain, heart, pancreas, skeletal muscle and testis; also detected in kidney, liver, lung, placenta, ovary and spleen; levels are low in leukocytes, colon, small intestine, prostate and thymus (PubMed:10364231). The N-terminal disordered region does not act as a key DNA-binding domain (PubMed:26704974). The WGR and PARP catalytic domains function together to recruit PARP2 to sites of DNA breaks. The N-terminal disordered region is only required for activation on specific types of DNA damage (PubMed:26704974). The WGR domain bridges two nucleosomes, with the broken DNA aligned in a position suitable for ligation (PubMed:30321391, PubMed:32939087, PubMed:33141820). The bridging induces structural changes in PARP2 that signal the recognition of a DNA break to the catalytic domain of PARP2, promoting HPF1 recruitment and subsequent activation of PARP2, licensing serine ADP-ribosylation of target proteins (PubMed:32939087). Auto poly-ADP-ribosylated on serine residues, leading to dissociation of the PARP2-HPF1 complex from chromatin (PubMed:32939087). Poly-ADP-ribosylated by PARP1 (By similarity). Acetylation reduces DNA binding and enzymatic activity. Belongs to the ARTD/PARP family. Catalysis - Issue 235 of April 2021