Ubiquitin (Ub) is a highly conserved protein found ubiquitously in eukaryotic organisms. The conjugation of ubiquitin to proteins is an important means to regulate protein activity for many cellular processes by tagging them for degradation. Removal of Ub can rescue proteins from degradation. This is accomplished by the ubiquitin-specific processing protease (UBP) family of enzymes. Ubiquitin specific processing protease 33 (USP33) is a member of this family.