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The Wayback Machine - http://web.archive.org/web/20060913000000/http://en.wikipedia.org:80/wiki/Guanylyl_cyclase_c
'''Guanylyl cyclase c''', or '''GC-C''', is an Enzyme found only in the luminal aspect of intestinal Epithelium. The receptor has an Extracellular Ligand-binding domain, a single Transmembrane_region, a region with sequence similar to that of Protein_kinases, and a C-terminal Guanylyl_cyclase domain. Tyrosine_kinase activity mediates the GC-C signaling pathway within the cell. ==Functions== GC-C is a key receptor for heat-stable Enterotoxins which are responsible for accute secretory Diarrhea. Heat-stable enterotoxins are produced by Pathogens such as ''Escherichia_coli''. Knockout mice defficient in the GC-C gene do not show secretory Diarrhea on infection with ''E. coli'', though they do with Cholera toxin. This demonstrates the specificity of the GC-C receptor. ==Diagnostic application== Because GC-C is tissue-specific for intestinal epithelium, it can be used for exceedingly precise detection of Metastatic_disease. The presence of GC-C MRNA can be detected at a rate of a single Cancer cell out of 10,000,000 normal cells. This is the most precise Staging tool available. ==External links== *GC-C testing for recurrent colorectal cancer *GC-C knock-out mice Category:EC_4.6.1