ID 3.4.22.38 DE Cathepsin K. AN Cathepsin O. AN Cathepsin O2. AN Cathepsin X. CA Broad proteolytic activity. With small-molecule substrates and CA inhibitors, the major determinant of specificity is P2, which is CA preferably Leu, Met > Phe, and not Arg. CC -!- Prominently expressed in mammalian osteoclasts, and believed to play CC a role in bone resorption. CC -!- Belongs to peptidase family C1. PR PROSITE; PDOC00126; DR Q5E968, CATK_BOVIN ; Q3ZKN1, CATK_CANFA ; Q90686, CATK_CHICK ; DR P43235, CATK_HUMAN ; P61276, CATK_MACFA ; P61277, CATK_MACMU ; DR P55097, CATK_MOUSE ; Q9GLE3, CATK_PIG ; P43236, CATK_RABIT ; DR O35186, CATK_RAT ; //