Cathepsin B
Lua error in Module:Infobox_gene at line 53: attempt to index field 'wikibase' (a nil value). Cathepsin B belongs to a family of lysosomal cysteine proteases known as the cysteine cathepsins and plays an important role in intracellular proteolysis.[1] In humans, cathepsin B is encoded by the CTSB gene.[2][3] Cathepsin B is upregulated in certain cancers, in pre-malignant lesions, and in various other pathological conditions.[4][5][6][7]
Structure
[edit | edit source]Gene
[edit | edit source]The CTSB gene is located at chromosome 8p22, consisting of 13 exons. The promoter of CTSB gene contains a GC-rich region including many SP1 sites, which is similar to housekeeping genes.[8] At least five transcript variants encoding the same protein have been found for this gene.[9]
Protein
[edit | edit source]Cathepsin B is synthesized on the rough endoplasmic reticulum as a preproenzyme of 339 amino acids with a signal peptide of 17 amino acids.[10][11] Procathepsin B of 43/46 kDa is then transported to the Golgi apparatus, where cathepsin B is formed. Mature cathepsin B is composed of a heavy chain of 25-26 kDa and a light chain of 5kDa, which are linked by a dimer of disulfide.
Function
[edit | edit source]Cathepsin B may enhance the activity of other proteases, including matrix metalloproteinase, urokinase (serine protease urokinase plasminogen activator), and cathepsin D,[12][13] and thus it has an essential position for the proteolysis of extracellular matrix components, intercellular communication disruption, and reduced protease inhibitor expression.[7]
Cells may become carcinogenic when cathepsin B is unregulated.[14]
Potential in disease
[edit | edit source]Cathepsin B has been proposed as a potentially effective biomarker for a variety of cancers.[12][15] Overexpression of cathepsin B is correlated with invasive and metastatic cancers.[16]
Cathepsin B has been shown to be involved in the pathogenesis of pancreatitis, by prematurely activating the digestive enzyme trypsinogen within the pancreas, leading to autodigestion of acinar cells.[17][18][19]
Interactions
[edit | edit source]Cathepsin B has been shown to interact with:
Cathepsin B is inhibited by:
See also
[edit | edit source]References
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Further reading
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External links
[edit | edit source]- The MEROPS online database for peptidases and their inhibitors: C01.060
- Cathepsin+B at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
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