A small peptide (guanylate cyclase-activating protein-2A, GCAP2A, 15 aa) found in vertebrate gut that binds to the intestine-specific receptor guanylate cyclase known as STaR (the receptor that binds bacterial heat-stable enterotoxins such as E.coli ST toxin; STa) and activates cGMP production. As a result of the elevated cGMP there is inhibition of salt absorption and stimulation of chloride secretion, accompanied by a massive accumulation of water in the gut, producing diarrhea and dehydration. Guanylin is generated from inactive 94-aa proguanylin. Uroguanylin (GCAP2B) is a similar peptide found in urine that may be involved in the regulation of electrolyte homeostasis by the kidney.
Subjects: Medicine and Health — Chemistry.