Component of the BRISC complex, a multiprotein complex that specifically cleaves 'Lys-63'-linked polyubiquitin, leaving the last ubiquitin chain attached to its substrates. May act as a central scaffold protein that assembles the various components of the BRISC complex and retains them in the cytoplasm (By similarity). 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. 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. Down-regulates the response to bacterial lipopolysaccharide (LPS) via its role in IFNAR1 deubiquitination. Required for normal induction of p53/TP53 in response to DNA damage. 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 (By similarity). Component of the BRISC complex, at least composed of ABRAXAS2, BRCC3/BRCC36, BABAM2 and BABAM1/NBA1. Interacts with BRCC3/BRCC36; the interaction is direct. Interacts with BABAM1. Does not interact with BRCA1. Interacts with SHMT1 and SHMT2; the interaction is direct. Identified in a complex with SHMT2 and the other subunits of the BRISC complex. The BRISC complex binds monoubiquitin and both 'Lys-48'- and 'Lys-63'-linked polyubiquitin. Identified in complexes with IFNAR1, IFNAR2 and SHMT2. Interacts with THAP5. Interacts with ATF4. Identified in a complex with p53/TP53 and USP7; interacts directly with both proteins. Interacts with NUMA1. Interacts with microtubule minus ends. Binds polyubiquitin. A minor proportion is detected in the nucleus. Translocates into the nucleus in response to DNA damage. Directly binds to microtubules and is detected at the minus end of K-fibers. Co-localizes with NUMA1 at mitotic spindle poles. 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.