CSTA Human, His

Cystatin A, also known as Stefin A, is a member of the cystatin superfamily of cysteine protease inhibitors. This protein plays a crucial role in inhibiting cysteine proteases, such as cathepsins B, H, and L, which are involved in various cellular processes including protein degradation, immune response, and apoptosis.

The recombinant human Cystatin A is typically produced in Escherichia coli (E. coli) expression systems. The protein is expressed as a single, non-glycosylated polypeptide chain containing 118 amino acids, with a molecular mass of approximately 13.1 kDa . To facilitate purification, a 6×His tag is fused to the N-terminus of the protein . This His tag allows for easy purification using nickel affinity chromatography.

Cystatin A functions as a potent inhibitor of cysteine proteases. It forms tight, reversible complexes with its target enzymes, thereby preventing the proteolytic activity of these enzymes. This inhibition is crucial for maintaining cellular homeostasis and protecting cells from unwanted proteolysis. Cystatin A is particularly important in the skin, where it contributes to the formation and maintenance of the cornified cell envelope in keratinocytes .

Recombinant Cystatin A is widely used in biochemical and biomedical research. Its ability to inhibit cysteine proteases makes it a valuable tool for studying protease function and regulation. Additionally, Cystatin A has been proposed as a potential prognostic and diagnostic marker for certain types of cancer . Researchers also use recombinant Cystatin A to investigate its role in various physiological and pathological processes.

For optimal stability, recombinant Cystatin A should be stored at -20°C to -80°C. After reconstitution, the protein solution is stable at -20°C for up to three months and at 2-8°C for up to one week. It is recommended to add a carrier protein or stabilizer, such as 0.1% BSA or 5% HSA, to prevent degradation during storage .