Hydrolase that can remove ‘Lys-48’-linked conjugated ubiquitin from proteins (PubMed:27292798). Binds to polyubiquitin chains of different linkage types, including ‘Lys-6’, ‘Lys-11’, ‘Lys-29’, ‘Lys-33’, ‘Lys-48’ and ‘Lys-63’ (PubMed:28082312). May play a regulatory role at the level of protein turnover (PubMed:27292798).