Deubiquitinating enzyme assays for novel USP17 subfamily members. In vitro deubiquitinating enzyme activity for USP17K, USP17L, USP17M, and USP17N. Immunoblotting analysis was performed with anti-β-gal antiserum. Coexpressed plasmids were pGEX-2TK (lane 1), pGEX-2TK-USP17K (lane 2), pGEX-2TK-USP17K (C89S) (lane 3), pGEX-2TK-USP17L (lane 4), pGEX-2TK-USP17L (C89S) (lane 5), pGEX-2TK-USP17M (lane 6), pGEX-2TK-USP17M (C89S) (lane 7), pGEX-2TK-USP17N (lane 8), and pGEX-2TK-USP17N (C89S) (lane 9). All of normal USP17 subfamily members cleaved the linkage between ubiquitin and β-galactosidase.