X-Ray Repair Cross Complementing (XRCC1) plays a role in excision repair of DNA after ionizing irradiation. XRCC1 binds to DNA ligase III through the C- terminal 96 amino acids and to DNA polymerase beta through the N-terminal half. In testis XRCC1 is expressed at high levels. Cells with a mutation of this gene exhibit 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.