Cystatin 8 (CST8)

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.

CST8 is located in the cystatin locus and encodes a protein similar to type 2 cystatins. The protein exhibits highly tissue-specific expression in the reproductive tract, suggesting implicit roles in reproduction. Alternative splicing identified in mouse is suggested in human based on EST evidence but the full-length nature of putative variants has not been determined.