【背景资料】:Isopeptidase-T (USP5) is a zinc-finger containing deubiquitinating enzyme (DUB) primarily responsible for the release of ubiquitin from unanchored polyubqiuitin chains. This activity allows isopeptidase-T to play a crucial role in the recycling of Ub and in the regulation of the proteasome activity and the degradation of ubiquitinated p53.