Component of the BRCA1-A complex, a complex that specifically recognizes '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). The BRCA1-A complex also possesses deubiquitinase activity that specifically removes 'Lys-63'-linked ubiquitin on histones H2A and H2AX (PubMed:17525341, PubMed:19261746, PubMed:19261749, PubMed:19261748). In the BRCA1-A complex, it acts as an adapter that bridges the interaction between BABAM1/NBA1 and the rest of the complex, thereby being required for the complex integrity and modulating the E3 ubiquitin ligase activity of the BRCA1-BARD1 heterodimer (PubMed:21282113, PubMed:19261748). Component of the BRISC complex, a multiprotein complex that specifically cleaves 'Lys-63'-linked ubiquitin in various substrates (PubMed:19214193, PubMed:24075985, PubMed:25283148, PubMed:26195665). Within the BRISC complex, acts as an adapter that bridges the interaction between BABAM1/NBA1 and the rest of the complex, thereby being required for the complex integrity (PubMed:21282113). The BRISC complex is required for normal mitotic spindle assembly and microtubule attachment to kinetochores via its role in deubiquitinating NUMA1 (PubMed:26195665). The BRISC complex plays a role in interferon signaling via its role in the deubiquitination of the interferon receptor IFNAR1; deubiquitination increases IFNAR1 activity by enhancing its stability and cell surface expression (PubMed:24075985). Down-regulates the response to bacterial lipopolysaccharide (LPS) via its role in IFNAR1 deubiquitination (PubMed:24075985). May play a role in homeostasis or cellular differentiation in cells of neural, epithelial and germline origins. May also act as a death receptor-associated anti-apoptotic protein, which inhibits the mitochondrial apoptotic pathway. May regulate TNF-alpha signaling through its interactions with TNFRSF1A; however these effects may be indirect (PubMed:15465831). Component of the ARISC complex, at least composed of UIMC1/RAP80, ABRAXAS1, BRCC3/BRCC36, BABAM2 and BABAM1/NBA1 (PubMed:21282113, PubMed:24075985). Component of the BRCA1-A complex, at least composed of BRCA1, BARD1, UIMC1/RAP80, ABRAXAS1, BRCC3/BRCC36, BABAM2 and BABAM1/NBA1. In the BRCA1-A complex, interacts directly with ABRAXAS1, BRCC3/BRCC36 and BABAM1/NBA1. Binds polyubiquitin. Component of the BRISC complex, at least composed of ABRAXAS2, BRCC3/BRCC36, BABAM2 and BABAM1/NBA1 (PubMed:19214193, PubMed:21282113, PubMed:24075985, PubMed:25283148). Identified in a complex with SHMT2 and the other subunits of the BRISC complex (PubMed:24075985). Component of the BRCA1/BRCA2 containing complex (BRCC), which also contains BRCA1, BRCA2, BARD1, BRCC3/BRCC36 and RAD51. BRCC is a ubiquitin E3 ligase complex that enhances cellular survival following DNA damage. May interact with FAS and TNFRSF1A (PubMed:15465831). Localizes at sites of DNA damage at double-strand breaks (DSBs). Additional isoforms may exist. Expressed in all cell lines examined. Highly expressed in placenta. Down-regulated by DNA-damaging agents in fibroblasts, by retinoic acid in brain glioma U-251MG and promyelocytic HL-60 cell lines, and by bacterial lipopolysaccharides (LPS) in peripheral blood mononuclear cells (PBMC). Contains 2 ubiquitin-conjugating enzyme family-like (UEV-like) regions. These regions lack the critical Cys residues required for ubiquitination but retain the ability to bind ubiquitin. Belongs to the BABAM2 family.