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Cystatin-B is a
GeneReviews/NCBI/NIH/UW entry on Unverricht-Lundborg Disease or EPM1
* The
I25.003
PDBe-KB
provides an overview of all the structure information available in the PDB for Human Cystatin-B {{gene-21-stub
Cystatin-B is a protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''CSTB'' gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
The cystatin superfamily encompasses proteins that contain multiple cystatin-like sequences. Some of the members are active cysteine protease
Cysteine proteases, also known as thiol proteases, are hydrolase enzymes that degrade proteins. These proteases share a common catalytic mechanism that involves a nucleophilic cysteine thiol in a catalytic triad or dyad.
Discovered by Gopal Chund ...
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
Papain, also known as papaya proteinase I, is a cysteine protease () enzyme present in papaya (''Carica papaya'') and mountain papaya (''Vasconcellea cundinamarcensis''). It is the namesake member of the papain-like protease family.
It has wide ...
and cathepsins L, H and B. The protein is thought to play a role in protecting against the proteases leaking from lysosome
A lysosome () is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane prot ...
s. Evidence indicates that mutations in this gene are responsible for the primary defects in patients with progressive myoclonic epilepsy
Myoclonic epilepsy refers to a family of epilepsies that present with myoclonus. It starts in both sides of the body at once, and last for more than a second or two. When myoclonic jerks are occasionally associated with abnormal brain wave activit ...
(EPM1).
Interactions
Cystatin B has been shown tointeract
Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization using innovative strategies to advocate for the legal and human rights of children with intersex traits. The organizati ...
with Cathepsin B.
References
Further reading
* * * * * * * * * * * * * * *External links
GeneReviews/NCBI/NIH/UW entry on Unverricht-Lundborg Disease or EPM1
* The
MEROPS
MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibitor ...
online database for peptidases and their inhibitorsI25.003
PDBe-KB
provides an overview of all the structure information available in the PDB for Human Cystatin-B {{gene-21-stub