Cathepsin C

Cathepsin C (also known as dipeptidyl peptidase I or DPPI) is a lysosomal exopeptidase enzyme that plays a crucial role in the activation of granule serine proteases. These proteases are involved in a variety of physiological processes, including immune response, inflammation, and apoptosis. Cathepsin C is encoded by the CTSC gene in humans.

Structure[edit | edit source]

Cathepsin C is a tetrameric enzyme composed of identical subunits. Each subunit consists of a heavy chain and a light chain, which are linked by a disulfide bond. The enzyme has a unique structure that allows it to selectively cleave dipeptides from the N-terminus of protein substrates.

Function[edit | edit source]

The primary function of Cathepsin C is to remove dipeptides from the N-terminus of protein substrates. This activity is essential for the activation of several serine proteases, including neutrophil elastase, cathepsin G, and proteinase 3. These proteases are stored in an inactive form in the granules of immune cells, and their activation is necessary for the cells to carry out their immune functions.

In addition to its role in immune response, Cathepsin C is also involved in the process of keratinocyte differentiation, which is important for the formation and maintenance of the skin barrier.

Clinical significance[edit | edit source]

Mutations in the CTSC gene that encodes Cathepsin C can lead to a rare genetic disorder known as Papillon-Lefevre syndrome. This condition is characterized by severe periodontitis and palmoplantar keratosis. Cathepsin C has also been implicated in a number of other diseases, including chronic obstructive pulmonary disease, cystic fibrosis, and rheumatoid arthritis.