Deubiquitinase involved in innate antiviral immunity by mediating 'Lys-48'-linked deubiquitination of CGAS, thereby promoting its stabilization. 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). Localizes to perinuclear region in response to herpes simplex virus-1 (HSV-1) infection. Predominantly expressed in brain and testis (PubMed:30919279). Highest expression levels in adult brain, especially in the cerebral cortex and hippocampus, and in the forebrain, face, and limb buds of midgestation mouse embryos (PubMed:10958632). No visible phenotype in normal conditions. Belongs to the peptidase C19 family.