Cystatin B

"CSTB" redirects here. For another use, see Trade Union Confederation of Bolivian Workers.

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Cystatin B, Human.

Cystatin-B is a protein that in humans is encoded by the CSTB gene.

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 kininogens. This gene encodes a stefin that functions as an intracellular cysteine protease inhibitor. The protein is able to form a dimer stabilized by noncovalent forces, inhibiting papain and cathepsins L, H and B. The protein is thought to play a role in protecting against the proteases leaking from lysosomes. Evidence indicates that mutations in this gene are responsible for the primary defects in patients with Unverricht–Lundborg disease, a form of progressive myoclonic epilepsy (EPM1).

Interactions

Cystatin B has been shown to interact with Cathepsin B.

External links

• GeneReviews/NCBI/NIH/UW entry on Unverricht-Lundborg Disease or EPM1
• The MEROPS online database for peptidases and their inhibitors: I25.003
• PDBe-KB provides an overview of all the structure information available in the PDB for Human Cystatin-B