Ubiquitin-binding protein involved in DNA repair and rescue of stalled ribosomes (PubMed:29144457, PubMed:32099016, PubMed:32579943, PubMed:36302773). Plays a role in DNA damage repair as component of the ASCC complex (PubMed:29144457). Recruits ASCC3 and ALKBH3 to sites of DNA damage by binding to polyubiquitinated proteins that have 'Lys-63'-linked polyubiquitin chains (PubMed:29144457). Part of the ASC-1 complex that enhances NF-kappa-B, SRF and AP1 transactivation (PubMed:12077347). Involved in activation of the ribosome quality control (RQC) pathway, a pathway that degrades nascent peptide chains during problematic translation (PubMed:32099016, PubMed:32579943, PubMed:36302773). Specifically recognizes and binds RPS20/uS10 ubiquitinated by ZNF598, promoting recruitment of the RQT (ribosome quality control trigger) complex on stalled ribosomes, followed by disassembly of stalled ribosomes (PubMed:36302773). {ECO:0000269|PubMed:12077347, ECO:0000269|PubMed:29144457, ECO:0000269|PubMed:32099016, ECO:0000269|PubMed:32579943, ECO:0000269|PubMed:36302773}. This is the function of ASCC2 (activating signal cointegrator 1 complex subunit 2, Ensembl gene identifier ENSG00000100325).