Deubiquitinating enzyme that removes conjugated ubiquitin from specific proteins to regulate different cellular processes. Thiol-dependent hydrolysis of ester, thioester, amide, peptide and isopeptide bonds formed by the C-terminal Gly of ubiquitin (a 76-residue protein attached to proteins as an intracellular targeting signal). Inhibited by ubiquitin aldehyde. Detected in brain, heart, liver, lung, kidney, ovary and spleen. Up-regulated by interleukin-3 (IL-3) in the B-lymphocyte cell line Ba/F3. May also be up-regulated in response to JAK2. Ubiquitinated. May be due to competing acceptor splice site. Belongs to the peptidase C19 family. USP17 subfamily.