A superfamily of structurally homologous cysteine peptidase inhibitors divided into family I (the stefins); family II (the cystatins), and family III (the kininogens). Cystatin C (cystatin 3, CSTC, 120 aa) is expressed in most tissues whereas cystatins D (cystatin 5), S (CST4), SN (CST1), and SA (CST2) are secreted in saliva. Cystatin C is excreted in urine and the serum concentration correlates with the glomerular filtration rate and has been suggested as a marker in testing for renal dysfunction. Mutations in CSTC are associated with Icelandic-type cerebroarterial amyloidosis.
Subjects: Chemistry — Medicine and Health.