Poly-ADP-ribosyltransferase that mediates poly-ADP-ribosylation of proteins and plays a key role in DNA repair. Mediates glutamate, aspartate, serine or tyrosine ADP-ribosylation of proteins: the ADP-D-ribosylgroup of NAD (+) is transferred to the acceptor carboxyl group of targetresidues and further ADP-ribosyl groups are transferred to the 2'-position of the terminal adenosine moiety, building up a polymer withan average chain length of 20-30 units. Serine ADP-ribosylation of proteins constitutes the primary form ofADP-ribosylation of proteins in response to DNA damage. Mainly mediates glutamate and aspartate ADP-ribosylation of target proteins in absence of HPF1. Following interaction with HPF1, catalyzes serineADP-ribosylation of target proteins; HPF1 conferring serine specificityby completing the PARP1 active site. Also catalyzes tyrosine ADP-ribosylation of target proteins following interaction with HPF1. PARP1 initiates the repair of DNAbreaks: recognizes and binds DNA breaks within chromatin and recruitsHPF1, licensing serine ADP-ribosylation of target proteins, such ashistones, thereby promoting decompaction of chromatin and therecruitment of repair factors leading to the reparation of DNA strandbreaks. In addition to baseexcision repair (BER) pathway, also involved in double-strand breaks (DSBs) repair: together with TIMELESS, accumulates at DNA damage sitesand promotes homologous recombination repair by mediating poly-ADP-ribosylation. Mediates the poly (ADP-ribosyl) ation of a number of proteins, including itself, APLF and CHFR. In addition to proteins, also ableto ADP-ribosylate DNA: catalyzes ADP-ribosylation of DNA strand breaktermini containing terminal phosphates and a 2'-OH group in single- anddouble-stranded DNA, respectively. Required for PARP9and DTX3L recruitment to DNA damage sites. PARP1-dependent PARP9-DTX3L-mediated ubiquitination promotes the rapid andspecific recruitment of 53BP1/TP53BP1, UIMC1/RAP80, and BRCA1 to DNAdamage sites. Acts as a regulator of transcription:positively regulates the transcription of MTUS1 and negativelyregulates the transcription of MTUS2/TIP150. Plays arole in the positive regulation of IFNG transcription in T-helper 1cells as part of an IFNG promoter-binding complex with TXK and EEF1A1. Involved in the synthesis of ATP in the nucleus, together with NMNAT1, PARG and NUDT5. Nuclear ATPgeneration is required for extensive chromatin remodeling events thatare energy-consuming. [1-7]

MAESSDKLYRVEYAKSGRASCKKCSESIPKDSLRMAIMVQSPMFDGKVPHWYHFSCFWKVGHSIRHPDVEVDGFSELRWDDQQKVKKTAEAGGVTGKGQDGIGSKAEKTLGDFAAEYAKSNRSTCKGCMEKIEKGQVRLSKKMVDPEKPQLGMIDRWYHPGCFVKNREELGFRPEYSASQLKGFSLLATEDKEALKKQLPGVKSEGKRKGDEVDGVDEVAKKKSKKEKDKDSKLEKALKAQNDLIWNIKDELKKVCSTNDLKELLIFNKQQVPSGESAILDRVADGMVFGALLPCEECSGQLVFKSDAYYCTGDVTAWTKCMVKTQTPNRKEWVTPKEFREISYLKKLKVKKQDRIFPPETSASVAATPPPSTASAPAAVNSSASADKPLSNMKILTLGKLSRNKDEVKAMIEKLGGKLTGTANKASLCISTKKEVEKMNKKMEEVKEANIRVVSEDFLQDVSASTKSLQELFLAHILSPWGAEVKAEPVEVVAPRGKSGAALSKKSKGQVKEEGINKSEKRMKLTLKGGAAVDPDSGLEHSAHVLEKGGKVFSATLGLVDIVKGTNSYYKLQLLEDDKENRYWIFRSWGRVGTVIGSNKLEQMPSKEDAIEHFMKLYEEKTGNAWHSKNFTKYPKKFYPLEIDYGQDEEAVKKLTVNPGTKSKLPKPVQDLIKMIFDVESMKKAMVEYEIDLQKMPLGKLSKRQIQAAYSILSEVQQAVSQGSSDSQILDLSNRFYTLIPHDFGMKKPPLLNNADSVQAKVEMLDNLLDIEVAYSLLRGGSDDSSKDPIDVNYEKLKTDIKVVDRDSEEAEIIRKYVKNTHATTHNAYDLEVIDIFKIEREGECQRYKPFKQLHNRRLLWHGSRTTNFAGILSQGLRIAPPEAPVTGYMFGKGIYFADMVSKSANYCHTSQGDPIGLILLGEVALGNMYELKHASHISKLPKGKHSVKGLGKTTPDPSANISLDGVDVPLGTGISSGVNDTSLLYNEYIVYDIAQVNLKYLLKLKFNFKTSLW