Deubiquitinating enzyme that removes conjugated ubiquitin from specific proteins to regulate different cellular processes. Has deubiquitinating enzyme activity for DNAH5, suggesting a role in the regulation of DNAH5 degradation by the ubiquitin-proteasome pathway. Has growth-suppressing activity; induces arrest in G1 phase upon controlled expression. 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). Expressed in hematopoietic progenitor cell lines Ba/F3 and FDCP1. Not detected in brain, lung, liver, kidney, thymus, spleen and bone marrow. Up-regulated by IL3, IL5 and CSF2. Polyubiquitinated; ubiquitination leads to its subsequent degradation. Belongs to the peptidase C19 family.