CST4
Description
The CST4 (cystatin S) is a protein-coding gene located on chromosome 20.
Cystatin-S is a protein encoded by the CST4 gene in humans. It belongs to the cystatin superfamily, which includes proteins with multiple cystatin-like sequences. Some of these proteins are active cysteine protease inhibitors, while others have lost or never acquired this inhibitory activity. Cystatin-S is a type 2 cystatin protein, a class of cysteine proteinase inhibitors found in various human fluids and secretions. The CST4 gene is located within the cystatin locus on chromosome 20, which contains a majority of the type 2 cystatin genes and pseudogenes. Cystatin-S is an S-type cystatin, characterized by its high expression in saliva, tears, and seminal plasma. Although its specific role in these fluids remains unclear, it exhibits antibacterial and antiviral activity, suggesting a protective function.
CST4 is also known as -.
