Deubiquitinating enzyme that removes conjugated ubiquitin from specific proteins to regulate different cellular processes that may include cell proliferation, progression through the cell cycle, apoptosis, cell migration, and the cellular response to viral infection. 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). Belongs to the peptidase C19 family. USP17 subfamily. The RS447 megasatellite DNA is a highly polymorphic conserved tandem repetitive sequence which contains a copy of the USP17 gene. It is present with an interindividual variation in copy number, ranging from 20 to 103, and can be found in the genome on chromosome 4 and chromosome 8. The high similarity between the UPS17-like genes makes it impossible to specifically assign data to a particular gene of the family. Oligonucleotides designed in RNAi experiments are for instance not specific for a given UPS17-like gene.