XRCC1 plays a key role in multiple DNA repair pathways by acting as a scaffold that binds to both DNA single strand breaks and gaps, poly (ADP-ribose) and to numerous DNA repair enzymes. It forms homodimers and interacts with polynucleotide kinase (PNK), DNA polymerase-beta (POLB), DNA ligase III (LIG3), APTX, APLF, and APEX1 [, ]. XRCC1 contains an N-terminal XRCC1-specific domain and two BRCT domains. This entry corresponds to the first (central) BRCT domain []. This domain has been shown to interact with poly(ADP-ribosyl)ated (PARylated) PARP1. Inactivation of the central X1BR1 domain results in DNA damage hypersensitivity due to a defect in S phase-dependent DNA repair [].
