Involved in the homologous recombination repair (HRR) pathway of double-stranded DNA, thought to repair chromosomal fragmentation, translocations and deletions. Part of the RAD51 paralog protein complex BCDX2 which acts in the BRCA1-BRCA2-dependent HR pathway. Upon DNA damage, BCDX2 acts downstream of BRCA2 recruitment and upstream of RAD51 recruitment. BCDX2 binds predominantly to the intersection of the four duplex arms of the Holliday junction and to junction of replication forks. The BCDX2 complex was originally reported to bind single-stranded DNA, single-stranded gaps in duplex DNA and specifically to nicks in duplex DNA (By similarity). Interacts with RAD51D. Part of the BCDX2 complex consisting of RAD51B, RAD51C, RAD51D and XRCC2; the complex has a ring-like structure arranged into a flat disk around a central channel. In the absence of DNA, the BCDX2 subcomplex XRCC2:RAD51D formed a multimeric ring structure; in the presence of single-stranded DNA it formed a filamentous structure with the ssDNA (By similarity). Expressed at low level in somatic tissues and at high level in testis. Belongs to the RecA family. RAD51 subfamily.