Component of the BRISC complex, a multiprotein complex that specifically cleaves 'Lys-63'-linked polyubiquitin, leaving the last ubiquitin chain attached to its substrates (PubMed:19214193, PubMed:20032457, PubMed:20656690, PubMed:24075985). May act as a central scaffold protein that assembles the various components of the BRISC complex and retains them in the cytoplasm (PubMed:20656690). Plays a role in regulating the onset of apoptosis via its role in modulating 'Lys-63'-linked ubiquitination of target proteins (By similarity). Required for normal mitotic spindle assembly and microtubule attachment to kinetochores via its role in deubiquitinating NUMA1 (PubMed:26195665). Plays a role in interferon signaling via its role in the deubiquitination of the interferon receptor IFNAR1; deubiquitination increases IFNAR1 activities by enhancing its stability and cell surface expression (PubMed:24075985, PubMed:26344097). Down-regulates the response to bacterial lipopolysaccharide (LPS) via its role in IFNAR1 deubiquitination (PubMed:24075985). Required for normal induction of p53/TP53 in response to DNA damage (PubMed:25283148). Independent of the BRISC complex, promotes interaction between USP7 and p53/TP53, and thereby promotes deubiquitination of p53/TP53, preventing its degradation and resulting in increased p53/TP53-mediated transcription regulation and p53/TP53-dependent apoptosis in response to DNA damage (PubMed:25283148). Component of the BRISC complex, at least composed of ABRAXAS2, BRCC3/BRCC36, BABAM2 and BABAM1/NBA1 (PubMed:19214193, PubMed:20032457, PubMed:21282113, PubMed:24075985, PubMed:25283148, PubMed:26344097, PubMed:26195665). Interacts with BRCC3/BRCC36; the interaction is direct (PubMed:20032457, PubMed:20656690, PubMed:26344097). Interacts with BABAM1 (PubMed:21282113). Does not interact with BRCA1 (PubMed:17525340, PubMed:21282113). Interacts with SHMT1 and SHMT2; the interaction is direct. Identified in a complex with SHMT2 and the other subunits of the BRISC complex (PubMed:24075985). The BRISC complex binds monoubiquitin and both 'Lys-48'- and 'Lys-63'-linked polyubiquitin (PubMed:20032457). Identified in complexes with IFNAR1, IFNAR2 and SHMT2 (PubMed:24075985). Interacts with THAP5 (PubMed:21195082). Interacts with ATF4 (PubMed:22974638). Identified in a complex with p53/TP53 and USP7; interacts directly with both proteins (PubMed:25283148). Interacts with NUMA1 (PubMed:26195665). Interacts with microtubule minus ends (PubMed:26195665). Binds polyubiquitin (PubMed:19261749). A minor proportion is detected in the nucleus (PubMed:21282113, PubMed:22974638). Translocates into the nucleus in response to DNA damage (PubMed:25283148). Directly binds to microtubules and is detected at the minus end of K-fibers (PubMed:26195665). Co-localizes with NUMA1 at mitotic spindle poles (PubMed:26195665). Detected in heart muscle (at protein level). Detected in heart and muscle, and at much lower levels in brain (PubMed:21195082). Up-regulated in response to DNA damage (PubMed:25283148). Up-regulated in myocardial infarction area (at protein level) (PubMed:21195082). Belongs to the FAM175 family. Abro1 subfamily. Although strongly related to the ABRAXAS1 protein, lacks the C-terminal pSXXF that constitutes a specific recognition motif for the BRCT domain of BRCA1. Extended N-terminus.