XRCC1 (X-Ray Repair Cross Complementing 1 Protein)

Recognizes a protein of 85kDa, identified as the X-Ray Repair Cross Complementing (XRCC1). The C-terminal 96 amino acids of XRCC1 are necessary and sufficient for the specific interaction with DNA ligase III of 103kDa. The region of interaction with DNA polymerase beta is located within residues 84-183 in the N-terminal half of the XRCC1 protein. Reportedly, Poly (ADP-ribose) polymerase also interacts with XRCC1. In testis XRCC1 is expressed at high levels. The XRCC1 gene plays a role for the sensitivity of mammalian cell lines toward ionizing irradiation. Cells with a mutation of this gene present with decreased single strand break repair and reduced recombination repair, they show increased double strand breaks, and sister chromatid exchange is increased up to 10-fold. The XRCC1 might serve as a scaffold protein during base excision-repair.