Cathepsin G
Unusual among cathepsins in belonging to the serine protease rather than cysteine or aspartic families, Cathepsin G (CTSG) is stored in the azurophilic granules of neutrophils and released during degranulation at sites of infection and inflammation. The enzyme is produced as a zymogen that is activated by Cathepsin C through removal of an N-terminal dipeptide. Cathepsin G cleaves a broad spectrum of substrates, including coagulation factors, chemokines, and receptors, and contributes to microbial killing, platelet activation, and cytokine modulation. Its expression is not restricted to neutrophils, as monocytes and some myeloid leukemia cells also produce the enzyme, which has been explored as a target for antithrombotic and anti-inflammatory drug development.
