UCH Proteins

The UCH (ubiquitin C-terminal hydrolase) family is a small branch of cysteine deubiquitinases comprising UCHL1, UCHL3, UCHL5 (UCH37) and the non-classical member BAP1. All share a catalytic ubiquitin C-terminal hydrolase domain of the papain-like fold with a Cys-His-Asp triad, and most additionally contain a crosslink (UCL) domain that restricts them to small ubiquitin adducts and chain ends. UCHL1 is neuron-specific and implicated in Parkinson's disease, UCHL3 is broadly expressed, and proteasome-associated UCHL5 trims chains during substrate degradation. Their preference for disassembling ubiquitin from small conjugates distinguishes them from the larger USP and OTU families, and UCH proteins are common targets of activity-based probes.