| Type: | Family | Name: | Peptidase C1A, cathepsin K |
| Description: | Cysteine peptidases have characteristic molecular topologies, which can be seen not only in their three-dimensional structures, but commonly also in the two-dimensional structures. These are peptidases in which the nucleophile is the sulphydryl group of a cysteine residue. Cysteine proteases are divided into clans (proteins which are evolutionary related), and further sub-divided into families, on the basis of the architecture of their catalytic dyad or triad []. This group of cysteine peptidases belong to the MEROPS peptidase family C1, sub-family C1A (papain family, clan CA).Cathepsin K is a cysteine protease expressed predominantly in osteoclasts. Activated cathepsin K cleaves key bone matrix proteins and is believed to play an important role in degrading the organic phase of bone during bone resorption. Cathepsin K is essential for normal bone resorption; Homo sapiens(Human) lacking cathepsin K exhibit pycnodysostosis, which is characterised by short stature and osteosclerosis []. Histological and radiographic analysis of the cathepsin K-deficient Mus musculus(Mouse) revealed osteoporosis of the long bones and vertebrae, and abnormal joint morphology []. | Short Name: | Peptidase_C1A_cathepsin-K |
