Recombinant Human Cystatin SN is produced with our mammalian expression system in human cells. The target protein is expressed with sequence (Trp21-Ser141) of Human CST1 fused with a polyhistidine tag at the C-terminus. Cystatin-SN is a member of family 2 of the Cystatin superfamily and a cysteine proteinase inhibitor found in saliva, tears, urine, and seminal fluid. Together with Cystatins S and SA, it is produced by the salivary gland and secreted largely in the submandibular/sublingual saliva. Cystatin-SN inhibits members of the Papain family including Cathepsins B, C, H and L.