Cystatin-B is a protein that in humans is encoded by the CSTB gene.^[5][6]

Quick Facts CSTB, Available structures ...

CSTB
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1STF, 2OCT, 4N6V
Identifiers
Aliases	CSTB, CST6, EPM1, EPM1A, PME, STFB, ULD, Cystatin B, CPI-B
External IDs	OMIM: 601145; MGI: 109514; HomoloGene: 79; GeneCards: CSTB; OMA:CSTB - orthologs
Gene location (Human) Chr. Chromosome 21 (human)[1] Band 21q22.3 Start 43,772,511 bp[1] End 43,776,330 bp[1]
Gene location (Mouse) Chr. Chromosome 10 (mouse)[2] Band 10 C1|10 39.72 cM Start 78,261,503 bp[2] End 78,263,456 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in oral cavity body of tongue gums cervix epithelium amniotic fluid vulva superior surface of tongue bronchial epithelial cell human penis vagina Top expressed in thymus skin of abdomen conjunctival fornix cornea ascending aorta corneal stroma cervix calvaria aortic valve lip More reference expression data BioGPS More reference expression data
Gene ontology Molecular function peptidase inhibitor activity protease binding endopeptidase inhibitor activity cysteine-type endopeptidase inhibitor activity RNA binding Cellular component cytoplasm nucleolus extracellular exosome intracellular anatomical structure nucleus extracellular region extracellular space cytosol secretory granule lumen tertiary granule lumen ficolin-1-rich granule lumen collagen-containing extracellular matrix Biological process adult locomotory behavior negative regulation of proteolysis negative regulation of peptidase activity negative regulation of endopeptidase activity neutrophil degranulation Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 1476 13014 Ensembl ENSG00000160213 ENSMUSG00000005054 UniProt P04080 Q62426 RefSeq (mRNA) NM_000100 NM_007793 RefSeq (protein) NP_000091 NP_031819 Location (UCSC) Chr 21: 43.77 – 43.78 Mb Chr 10: 78.26 – 78.26 Mb PubMed search [3] [4]
Wikidata
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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).^[6]

Cystatin B has been shown to interact with Cathepsin B.^[7][8]