Cathepsin K

1MEM, 3KWB, 3KX1, 4X6J, 1AYW, 3KW9, 1YT7, 1AU2, 4X6H, 1Q6K, 1YK7, 1ATK, 3C9E, 1AYV, 1BGO, 4N8W, 7PCK, 4DMX, 4X6I, 1NL6, 1TU6, 3O0U, 1AU4, 3OVZ, 3KWZ, 2ATO, 3O1G, 1AU0, 1BY8, 1SNK, 2AUZ, 4DMY, 4N79, 1AYU, 1U9X, 1YK8, 1AU3, 1U9V, 2BDL, 1VSN, 1U9W, 2AUX, 2R6N, 3H7D, 1NLJ, 5J94, 4YVA, 4YV8151313038ENSG00000143387ENSMUSG00000028111P43235P55097NM_000396NM_007802NP_000387NP_031828Cathepsin K, abbreviated CTSK, is an enzyme that in humans is encoded by the CTSK gene.Osteoclast1atk: CRYSTAL STRUCTURE OF THE CYSTEINE PROTEASE HUMAN CATHEPSIN K IN COMPLEX WITH THE COVALENT INHIBITOR E-641au0: CRYSTAL STRUCTURE OF THE CYSTEINE PROTEASE HUMAN CATHEPSIN K IN COMPLEX WITH A COVALENT SYMMETRIC DIACYLAMINOMETHYL KETONE INHIBITOR1au2: CRYSTAL STRUCTURE OF THE CYSTEINE PROTEASE HUMAN CATHEPSIN K IN COMPLEX WITH A COVALENT PROPANONE INHIBITOR1au3: CRYSTAL STRUCTURE OF THE CYSTEINE PROTEASE HUMAN CATHEPSIN K IN COMPLEX WITH A COVALENT PYRROLIDINONE INHIBITOR1au4: CRYSTAL STRUCTURE OF THE CYSTEINE PROTEASE HUMAN CATHEPSIN K IN COMPLEX WITH A COVALENT PYRROLIDINONE INHIBITOR1ayu: CRYSTAL STRUCTURE OF CYSTEINE PROTEASE HUMAN CATHEPSIN K IN COMPLEX WITH A COVALENT SYMMETRIC BISCARBOHYDRAZIDE INHIBITOR1ayv: CRYSTAL STRUCTURE OF CYSTEINE PROTEASE HUMAN CATHEPSIN K IN COMPLEX WITH A COVALENT THIAZOLHYDRAZIDE INHIBITOR1ayw: CRYSTAL STRUCTURE OF CYSTEINE PROTEASE HUMAN CATHEPSIN K IN COMPLEX WITH A COVALENT BENZYLOXYBENZOYLCARBOHYDRAZIDE INHIBITOR1bgo: CRYSTAL STRUCTURE OF CYSTEINE PROTEASE HUMAN CATHEPSIN K IN COMPLEX WITH A COVALENT PEPTIDOMIMETIC INHIBITOR1by8: THE CRYSTAL STRUCTURE OF HUMAN PROCATHEPSIN K1mem: CRYSTAL STRUCTURE OF CATHEPSIN K COMPLEXED WITH A POTENT VINYL SULFONE INHIBITOR1nl6: Crystal Structure Of The Cysteine Protease Human Cathepsin K In Complex With A Covalent Azepanone Inhibitor1nlj: CRYSTAL STRUCTURE OF THE CYSTEINE PROTEASE HUMAN CATHEPSIN K IN COMPLEX WITH A COVALENT AZEPANONE INHIBITOR1q6k: Cathepsin K complexed with t-butyl(1S)-1-cyclohexyl-2-oxoethylcarbamate1snk: Cathepsin K complexed with carbamate derivatized norleucine aldehyde1tu6: Cathepsin K complexed with a ketoamide inhibitor1u9v: Crystal Structure of the Cysteine Protease Human Cathepsin K in Complex with the Covalent Inhibitor NVP-ABE8541u9w: Crystal Structure of the Cysteine Protease Human Cathepsin K in Complex with the Covalent Inhibitor NVP-ABI4911u9x: Crystal Structure of the Cysteine Protease Human Cathepsin K in Complex with the Covalent Inhibitor NVP-ABJ6881vsn: Crystal structure of a potent small molecule inhibitor bound to cathepsin K1yk7: Cathepsin K complexed with a cyanopyrrolidine inhibitor1yk8: Cathepsin K complexed with a cyanamide-based inhibitor1yt7: Cathepsin K complexed with a constrained ketoamide inhibitor2ato: Crystal structure of Human Cathepsin K in complex with myocrisin2aux: Cathepsin K complexed with a semicarbazone inhibitor2auz: Cathepsin K complexed with a semicarbazone inhibitor2bdl: Cathepsin K complexed with a pyrrolidine ketoamide-based inhibitor2f7d: A mutant rabbit cathepsin K with a nitrile inhibitor2ftd: Crystal structure of Cathepsin K complexed with 7-Methyl-Substituted Azepan-3-one compound7pck: CRYSTAL STRUCTURE OF WILD TYPE HUMAN PROCATHEPSIN K Cathepsin K, abbreviated CTSK, is an enzyme that in humans is encoded by the CTSK gene. The protein encoded by this gene is a lysosomal cysteine protease involved in bone remodeling and resorption. This protein, which is a member of the peptidase C1 protein family, is expressed predominantly in osteoclasts. Cathepsin K is a protease, which is defined by its high specificity for kinins, that is involved in bone resorption. The enzyme's ability to catabolize elastin, collagen, and gelatin allows it to break down bone and cartilage. This catabolic activity is also partially responsible for the loss of lung elasticity and recoil in emphysema. Cathepsin K inhibitors show great potential in the treatment of osteoporosis. Cathepsin K is degraded by Cathepsin S, called Controlled Cathepsin Cannibalism. Cathepsin K expression is stimulated by inflammatory cytokines that are released after tissue injury. Cathepsin K is expressed in a significant fraction of human breast cancers, where it could contribute to tumor invasiveness. Mutations in this gene are the cause of pycnodysostosis, an autosomal recessive disease characterized by osteosclerosis and short stature. Cathepsin K has also been found to be over-expressed in glioblastoma. That the expression of cathepsin K is characteristic for some cancers and not others has been documented. Cathepsin K antibodies are marketed for research into expression of this enyzme by various cells. Merck had a cathepsin K inhibitor, odanacatib, in Phase III clinical trials for osteoporosis. In September, 2016, Merck announced they were discontinuing development of odanacatib after their own assessment of adverse events and an independent assessment showed increased risk of stroke. Other cathepsin K inhibitors are in various stages of development. Medivir has a cathepsin K inhibitor, MIV-711 (L-006235), in Phase IIa clinical trial, as a disease modifying osteoarthritis drug, as of October 2017.