Recombinant Human Cystatin S protein (His tag N-Terminus)

Supplementary information

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

Cystatin S also known as CST4 is a cysteine protease inhibitor with a molecular mass of approximately 14 kDa. This protein belongs to the cystatin superfamily which is a group of proteins that inhibit proteases such as cathepsins. Cystatin S is mainly expressed in human saliva tears and other bodily fluids where it plays a significant role in protecting tissues from protease activity. Expression levels of cystatin S vary across tissues and can influence its inhibitory functions.

Biological function summary

Cystatin S regulates proteolytic activity by inhibiting enzymes like papain and cathepsins. This protein aids in maintaining the equilibrium between proteases and their inhibitors which is essential for protecting extracellular matrices. Cystatin S does not form part of a larger complex but functions independently to provide defense against unwanted proteolysis in the oral cavity and other environments.

Pathways

Cystatin S interacts with proteolytic pathways that handle extracellular matrix degradation and inflammatory responses. Inhibiting cathepsins within these pathways counters tissue destruction and contributes to cellular homeostasis. Cystatin-related proteins such as cystatin C share similar inhibitory roles indicating their importance in overlapping regulatory networks.

Aberrant expression or function of cystatin S associates with conditions like periodontitis and Sjögren's syndrome. In periodontitis imbalance in protease inhibition leads to periodontal tissue breakdown. Sjögren's syndrome characterized by reduced secretion of tears and saliva links to altered cystatin S levels and its interaction with other protease inhibitors like cystatin C. Both disorders highlight the significance of cystatin S in maintaining tissue integrity.