Guanylate cyclase 2C, also known as guanylyl cyclase C (GC-C), intestinal guanylate cyclase, guanylate cyclase-C receptor, or the heat-stable enterotoxin receptor (hSTAR) is an enzyme that in humans is encoded by the GUCY2Cgene.
GC-C is a key receptor for heat-stable enterotoxins that are responsible for acute secretory diarrhea. Heat-stable enterotoxins are produced by pathogens such as Escherichia coli. Knockout mice deficient 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.
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.