Protein Domain : Cystatin-9-like IPR043250

Type	Family
Description	Cystatins (also known as cysteine proteinase inhibitors) are structurally conserved, low molecular weight endogenous cysteine protease inhibitors found in most body compartments and fluids. They play an intra and/or extra-cellular role to inhibit cysteine enzymes (i.e cathepsins), crucial to maintain the protease-inhibitor balance, thus regulating damaging proteolytic activities [ ]. It is thought that cystatins may influence the intra- and extracellular catabolism of proteins and peptides, regulate proteolytic processing of prohormones and proenzymes, protect against penetration of normal tissues by malignant cells or microorganisms and modulate local inflammatory processes such as rheumatoid arthritis and purulent bronchiectasis [].Cystatins have been categorised into three classes. Stefins (type I) are unglycosylated proteins of about 100 amino acids lacking disulphide bridges. Type II cystatins are about 120 amino acids and have two intra-chain disulphide bonds. Most of them are found both in tissues and body fluids including saliva. Kininogens (type III) are single chain glycoproteins containing three cystatin-like domains [ ].Cystatin 9 (CST9) is a small ~18kDa human protein member of the type 2 cystatin superfamily [ ]. It may play a role in hematopoietic differentiation or inflammation. It may be targeted through the Golgi via the secretory pathway []. It has been shown to have immunomodulatory and antibacterial effects against Francisella tularensis infection of the lung [].This entry represents cystatin 9 and cystatin 9-like proteins.
Short Name	CST9-like