Definition: A homologous group of endogenous CYSTEINE PROTEINASE INHIBITORS. The cystatins inhibit most CYSTEINE ENDOPEPTIDASES such as PAPAIN, and other peptidases which have a sulfhydryl group at the active site.
Other names Cystatin Superfamily; Cystatins, Type III; Cystatins, Type II; Cystatins, Type I; Cystatins, Type 3; Cystatins, Type 2; Cystatins, Type 1; Cystatin Related Proteins; Type III Cystatins; Type II Cystatins; Type I Cystatins; Type 3 Cystatins; Type 2 Cystatins; Type 1 Cystatins; Cystatin-Related Proteins; Stefins