CST5, also known as Cystatin-D, is a novel member of the cystatin superfamily. The cystatin superfamily encompasses proteins that contain multiple cystatin-like sequences. Some of the members are active cysteine protease inhibitors, while others have lost or perhaps never acquired this inhibitory activity. There are three inhibitory families in the superfamily, including the type 1 cystatins (stefins), type 2 cystatins and the kininogens. The type 2 cystatin proteins are a class of cysteine proteinase inhibitors found in a variety of human fluids and secretions. Two alleles of the cystatin D gene (CST5), encoding protein variants with either Cys or Arg as residue 26 in their 122- residue polypeptide chains, are present in the population. Source: Recombinant protein corresponding to aa26-142 from human CST5, fused to His-tag at C-terminal expressed in insect cell. Molecular Weight: ~14.36kD (123aa) Amino Acid Sequence: QSRTLAGGIH ATDLNDKSVQ RALDFAISEY NKVINKDEYY SRPLQVMAAY QQIVGGVNYY FNVKFGRTTC TKSQPNLDNC PFNDQPKLKE EEFCSFQINE VPWEDKISIL NYKCRKVHHH HHH Storage and Stability: May be stored at 4C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20C. Aliquots are stable for 6 months after receipt at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.