Recombinant Human Cystatin SN/CST1 protein

Supplementary information

This supplementary information is collated from multiple sources and compiled automatically.

Cystatin SN also known as CST1 is a cysteine protease inhibitor that belongs to the family of cystatins. This protein has a mass of approximately 16 kDa and is expressed primarily in human saliva as well as other tissues like the nasal mucosa and skin. Its main role involves binding to and inhibiting cathepsins and other cysteine protease enzymes preventing the breakdown of cellular and extracellular proteins. Such inhibition protects tissues from damage and helps maintain normal protein turnover.

Biological function summary

CST1 inhibits proteolytic enzymes that are involved in degrading proteins within cells and tissues. This protein is not part of a larger complex but instead exerts its function through one-on-one interactions with target proteases. Through its inhibitory actions CST1 plays a protective role in various bodily fluids and epithelial surfaces contributing to the body's barrier and immune defense mechanisms against pathogens and tissue damage.

Pathways

CST1 is engaged in the regulation of protease activity which impacts the broader proteolytic pathways that are important to cellular homeostasis. This regulation is linked to the lysosomal cathepsin family and pathways such as the protein metabolism pathway. Related proteins within these pathways include cathepsin L and cathepsin B which are also cysteine proteases that rely on precise regulation by cystatin family proteins like CST1 to prevent excessive protein degradation.

CST1 has associations with conditions like chronic rhinosinusitis and certain cancers. Chronic rhinosinusitis involves excessive inflammation and tissue damage a process where CST1's inhibition of proteases like cathepsin B is important. In cancer abnormal CST1 expression levels have been noted in gastric and colorectal cancers suggesting a connection with tumor growth and metastasis. In these contexts altered expression or function of CST1 may interact with other proteins such as cathepsin L influencing disease progression.