Biology:CagA
| Cytotoxicity-associated immunodominant antigen | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Organism | |||||||
| Symbol | CagA | ||||||
| UniProt | P55980 | ||||||
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Cytotoxicity-associated immunodominant antigen (CagA), also CAG pathogenicity island protein 26, is a 120–145kDa protein encoded on the 40kb CAG pathogenicity island of Helicobacter pylori.[1] CagA is the major virulence factor of H. pylori.
H. pylori strains can be divided into CagA positive or negative strains. Approximately 60% of H. pylori strains isolated in Western countries carry cag PAI, whereas almost all of the East Asian isolates are cag PAI-positive.[1][dubious ]
The cag PAI also encodes for a type IV secretion system which is used to "inject" CagA into a target cell upon H. pylori attachment. After translocation, CagA localises to the inner surface of the cell membrane and undergoes tyrosine phosphorylation by Src family kinases (e.g. Fyn and Lyn).[1]
Role in cancer
H. pylori infection is associated with MALT lymphoma and gastric adenocarcinoma and CagA is thought to be involved in cancer development.[2] Phosphorylated CagA is able to interact with the SHP-2 tyrosine phosphatase, rendering it functionally active, triggering a host cell morphological change to a more motile phenotype known as the "hummingbird phenotype".[1] This phenotype mimics an effect produced by hepatocyte growth factor which may participate in various aspects of cancer, including metastasis.[2] CagA is also a highly antigenic protein that is associated with a prominent inflammatory response by eliciting interleukin-8 production.[3]
The Cag PAI
 | This section is missing information about what else is on it -- it's 30 or so ORFs!. (January 2022) |
References
- ↑ 1.0 1.1 1.2 1.3 "Helicobacter pylori CagA: a new paradigm for bacterial carcinogenesis". Cancer Science 96 (12): 835–843. December 2005. doi:10.1111/j.1349-7006.2005.00130.x. PMID 16367902.
- ↑ 2.0 2.1 "Opinion: Bacterial toxins and cancer--a case to answer?". Nature Reviews. Microbiology 3 (4): 343–349. April 2005. doi:10.1038/nrmicro1130. PMID 15806096.
- ↑ "Mechanisms of disease: Helicobacter pylori virulence factors". Nature Reviews. Gastroenterology & Hepatology 7 (11): 629–641. November 2010. doi:10.1038/nrgastro.2010.154. PMID 20938460.
External links
- "Search: "cytotoxin-associated gene A" "Helicobacter pylori"". Protein. NCBI. https://www.ncbi.nlm.nih.gov/protein/?term=%22cytotoxin-associated+gene+A%22+%22Helicobacter+pylori%22.
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