InterPro domain: IPR045080

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 [ 1 , 2 ]. XRCC1 contains an N-terminal XRCC1-specific domain and two BRCT domains. This entry corresponds to the first (central) BRCT domain [ 3 ]. 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 [ 4 ].

1. XRCC1 and DNA strand break repair. DNA Repair (Amst) 2, 955-69
2. The structural basis for partitioning of the XRCC1/DNA ligase III-α BRCT-mediated dimer complexes. Nucleic Acids Res. 39, 7816-27
3. Specificity of protein interactions mediated by BRCT domains of the XRCC1 DNA repair protein. J Biol Chem 280, 30206-13
4. An atypical BRCT-BRCT interaction with the XRCC1 scaffold protein compacts human DNA Ligase IIIα within a flexible DNA repair complex. Nucleic Acids Res 49, 306-321