Stefins are members of the cystatin superfamily of cysteine proteinase inhibitors localized in the cytosol and thought to protect cytoskeletal proteins from degradation by cysteine proteases released from lysosomes.
Type I or family 1 of the cystatin superfamily of cysteine protease inhibitors includes human stefins A and B and their homologues in other species such as cystatinsα and β in rat, bovine thymus stefin C, porcine thymus stefins D1 and D2, mouse stefin A (1–4), and others (see MEROPS subfamily I25A). The genes for human stefins A and B have been mapped to chromosomes 3q21 and 21q22.3, respectively. The lack of a signal sequence and disulfide bonds makes stefins distinct from other members of the cystatin superfamily. Stefins are single-chain proteins consisting of 98–103 amino acid residues, with a molecular mass of 11–12 kDa. Human stefin A is an acidic protein with pI values between 4.5 and 5.0, whereas...
KeywordsCysteine Protease Cysteine Protease Inhibitor Cysteine Protease Activity Cysteine Cathepsin Psoriatic Epidermis
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