Guanylin
Protein family
From Wikipedia, the free encyclopedia
Guanylin is a 15 amino acid peptide that is secreted by goblet cells in the colon. Guanylin acts as an agonist of the guanylyl cyclase receptor GC-C and regulates electrolyte and water transport in intestinal and renal epithelia.[2][3] Upon receptor binding, guanylin increases the intracellular concentration of cGMP, induces chloride secretion and decreases intestinal fluid absorption, ultimately causing diarrhoea.[4] The peptide stimulates the enzyme through the same receptor binding region as the heat-stable enterotoxins.[3]
Researches have found that a loss in guanylin expression can lead to colorectal cancer due to guanylyl cyclase C's function as an intestinal tumor suppressor.[5] When guanylin expression was measured on over 250 colon cancer patients, more than 85% of patients had a loss of guanylin expression in cancerous tissue samples by 100-1000 times when compared to the same patients's nearby healthy colon tissue.[5] Another study done on genetically engineered mice found that mice on a high calorie diet had reduced guanylin expression in the colon.[6] This loss of expression then resulted in guanylyl cyclase C inhibition and the formation of tumors, therefore linking diet-induced obesity with colorectal cancer. [6]
Human proteins containing this domain
GUCA2A; GUCA2B;
