Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a key role in DNA repair (PubMed:10364231). 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 (By similarity). Serine ADP-ribosylation of proteins constitutes the primary form of ADP-ribosylation of proteins in response to DNA damage (By similarity). Mediates glutamate and aspartate ADP-ribosylation of target proteins in absence of HPF1 (By similarity). Following interaction with HPF1, catalyzes serine ADP-ribosylation of target proteins; HPF1 conferring serine specificity by completing the PARP2 active site (By similarity). 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 (By similarity). In addition to proteins, also able to ADP-ribosylate DNA: preferentially acts on 5'-terminal phosphates at DNA strand breaks termini in nicked duplex (By similarity). 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 (PubMed:11948190). Interacts (via the PARP catalytic domain) with HPF1 (By similarity). Interacts with core nucleosomes. Homo- and heterodimer with PARP1 (By similarity). Recruited to DNA damage sites. Widely expressed; the highest levels were in testis followed by ovary (PubMed:11133988). Expression is correlated with proliferation, with higher levels occurring during early fetal development and organogenesis and in the highly proliferative cell compartments of adult (PubMed:11948190). At stage 12.5 dpc, expressed at high level in the developing liver and kidneys (PubMed:11948190). At 18.5 dpc, preferentially expressed in the thymus and in regions of the nervous system (PubMed:11948190). Within the developing trunk, preferential expression persisted in the liver and became restricted to the cortical region of the kidney, spleen, adrenal gland, and to stomach and intestinal epithelia (PubMed:11948190). From 14.5 dpc to 18.5 dpc, as well as in the adult, expressed at the highest level in thymus (PubMed:11948190). Expression is particularly high in the subcapsular zone of the thymus where immature lymphocytes proliferate (PubMed:11948190). By high levels of DNA-damaging agents. The N-terminal disordered region does not act as a key DNA-binding domain. 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. The WGR domain bridges two nucleosomes, with the broken DNA aligned in a position suitable for ligation. 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. Auto poly-ADP-ribosylated on serine residues, leading to dissociation of the PARP2-HPF1 complex from chromatin (By similarity). Poly-ADP-ribosylated by PARP1 (PubMed:11948190). Acetylation reduces DNA binding and enzymatic activity. No visible phenotype in normal conditions, but mutant mice are sensitive to ionizing radiation (PubMed:12727891). Following alkylating agent treatment, cells show increased post-replicative genomic instability, G2/M accumulation and chromosome missegregation accompanying kinetochore defects (PubMed:12727891). Mice lacking both Parp1 and Parp2 are not viable and die at the onset of gastrulation (PubMed:12727891). Belongs to the ARTD/PARP family.