A DNA damage-independent phosphorylation of FAM175A (Abraxas) serine residue S406 creates a pS-X-X-F (phospho-Ser-X-X-Phe) motif that binds BRCT repeats of BRCA1. The BRCA1 cancer predisposing mutation M1775R (Met1775Arg) inhibits BRCA1 binding to FAM175A. FAM175A interaction with UIMC1 (RAP80) enables BRCA1 recruitment to DNA double strand breaks (DSBs) (Wang et al. 2007). In addition to BRCA1, FAM175A also interacts with BRCC3 (BRCC36) (Wang et al. 2007, Hu et al. 2011) and BABAM1 (MERIT40, NBA1) (Vikrant et al. 2014). BABAM1 simultaneously interacts with BRE (BRCC45) (Hu et al. 2011). Together, BRCA1, BARD1, UIMC1, FAM175A, BRCC36, BRE and BABAM1 form the so-called BRCA1-A complex at DNA DSBs (Wang et al. 2009).