BRCA2 and RAD51 interact directly through the highly conserved BRCT repeats in BRCA2 (Venkitaraman 2002). CHEK1-mediated phosphorylation of BRCA2 (at threonine residue T3387) and RAD51 (at threonine residue T309) facilitates their binding (Sorensen et al. 2005, Bahassi et al. 2008). One BRCA2 can bind up to six RAD51 molecules, thus playing an important role in RAD51 nucleation at the dsDNA-ssDNA junction created by resection of DNA double strand breaks (DSBs) (Liu et al. 2010, Thorslund et al. 2010, Jensen et al. 2010). After the nucleation step, additional RAD51 molecules bind the ssDNA and multimerize, forming RAD51 nucleoprotein filaments (Yang et al. 2005). BRCA2-mediated RAD51 loading displaces the RPA complex from 3' overhanging ssDNA at DSBs (Sugiyama et al. 1997, Jensen et al. 2010), presumably with other RPA-bound proteins, such as ATR:ATRIP and complexes involved in ATR catalytic activation.