Deubiquitinase with endodeubiquitinase activity that preferentially cleaves 'Lys-48'-linked polyubiquitin chains (PubMed:29576528, PubMed:29476094). Shows only weak activity against 'Lys-63' and 'Lys-11'-linked chains (PubMed:29476094). Has a role in meiosis (PubMed:16303567). 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). kcat is 7.2 sec(-1) with Arg-Leu-Arg-Gly-Gly-AMC as substrate. Belongs to the peptidase C78 family. ZUFSP subfamily.