Protease that can remove conjugated ubiquitin from target proteins and polyubiquitin chains .Inhibits the degradation of target proteins by the proteasome .
Cleaves preferentially 'Lys-6' and 'Lys-63'-linked ubiquitin chains. Has lower activity with 'Lys-11' and 'Lys-33'-linked ubiquitin chains, and extremely low activity with 'Lys-27', 'Lys-29' and 'Lys-48'-linked ubiquitin chains (in vitro).Plays a role in the regulation of pathways leading to NF-kappa-B activation.Plays a role in the regulation of DNA repair after double-stranded DNA breaks .Acts as a chromatin regulator via its association with the Polycomb group (PcG) multiprotein PRC1-like complex; may act by deubiquitinating components of the PRC1-like complex .Promotes cell proliferation by deubiquitinating phosphorylated E2F1 .