A subfamily of the cystatins which are cysteine peptidase inhibitors. Stefin A (cystatin A, keratolinin, 98 aa) inhibits cathepsins D, B, H, and L and is found in neutrophils, spleen, liver, and epidermis (as keratolinin). Stefin B (cystatin B, 98 aa) has antipeptidase activity but also interacts with several proteins and coimmunoprecipitates with RACK1, β-spectrin, and neurofilament light chain (NFL) in rat cerebellum. Mutations in stefin B are associated with myoclonic epilepsy of Unverricht and Lundborg.
Subjects: Medicine and Health.