This gene encodes a member of the C1 family of peptidases and a lysosomal cysteine proteinase that appears to be a central coordinator for the activation of many serine proteinases in cells of the immune system. Alternative splicing results in multiple transcript variants, at least one of which encodes a preprotein that is proteolytically processed to form heavy and light chains that form a disulfide-linked dimer. A portion of the propeptide acts as an intramolecular chaperone for folding and stabilization of the mature enzyme. This enzyme requires chloride ions for its activity and can degrade glucagon. Defects in the encoded protein have been shown to cause Papillon-Lefevre syndrome, an autosomal recessive disorder characterized by palmoplantar keratosis and periodontitis.
Cathepsin C functions as a key enzyme in the activation of granular serine peptidases in inflammatory cells, such as elastase and cathepsin G in neutrophils and chymase and tryptase in mast cells. In many inflammatory diseases such as rheumatoid arthritis, chronic obstructive pulmonary disease (COPD), inflammatory bowel disease, asthma, sepsis, and cystic fibrosis, a significant part of the pathogenesis is due to increased activity of some of these inflammatory proteases. Once activated by cathepsin C, these proteases can degrade various extracellular matrix components, leading to tissue damage and chronic inflammation.
Related metabolic pathways include transport to the Golgi and subsequent modification and metabolism of proteins. Gene Ontology (GO) annotations for this gene include identical protein binding and cysteine-type peptidase activity.