BRISC and BRCA1-A complex member 1 (BABAM1, also known as MERIT40 and NBA1) was initially identified as a gene required for resistance to ionizing radiation []. It is a component of the BRCA1-A complex, which also contains Brca1/Bard1, Abra1, RAP80, BRCC36, and BRE []. The BRCA1-A complex recognises 'Lys-63'-linked ubiquitinated histones H2A and H2AX at DNA lesions sites, leading to target the brca1-bard1 heterodimer to sites of DNA damage at double-strand breaks (DSBs), facilitating DNA damage repair. The BRCA1-A complex is also involved in G2/M transition DNA damage checkpoint control. BABAM1 may also play a role as a component of the BRISC complex (contains the FAM175B/ABRO1, BRCC3/BRCC36, BRE/BRCC45 and MERIT40/NBA1 proteins), a multiprotein complex that specifically cleaves 'Lys-63'-linked ubiquitin. In these 2 complexes, BABAM1 is probably required to maintain the stability of BRE/BRCC45 and help the 'Lys-63'-linked deubiquitinase activity mediated by BRCC3/BRCC36 component [, ].
