Cystatin C

Cystatin C or cystatin 3 (formerly gamma trace, post-gamma-globulin, or neuroendocrine basic polypeptide), is a protein encoded by the CST3 gene. In humans most nucleated cells produce cystatin C as a polypeptide of 120 amino acids. It is found in virtually all tissues and body fluids. Functionally, it is a potent inhibitor of lysosomal proteinases and an important extracellular inhibitor of cysteine proteases. Cystatin C belongs to the type 2 cystatin gene family. In medicine Cystatin C is most commonly known as a biomarker of kidney function. Additionally it has a role in predicting cardiovascular disease, and may play a role in brain disorders involving amyloid such as Alzheimer's disease.