FunctionClosely involved in osteoclastic bone resorption and may participate partially in the disorder of bone remodeling. Displays potent endoprotease activity against fibrinogen at acid pH. May play an important role in extracellular matrix degradation.
Tissue specificityPredominantly expressed in osteclasts (bones).
Involvement in diseaseDefects in CTSK are the cause of pycnodysostosis (PKND) [MIM:265800]. PKND is an autosomal recessive osteochondrodysplasia characterized by osteosclerosis and short stature.
Sequence similaritiesBelongs to the peptidase C1 family.