Main Page | See live article | Alphabetical index cGMP (or 3'-5'-cyclic GMP) is a second messenger molecule, used for intracellular signal transduction. It is made from GTP by guanylate cyclase. Its main purpose is the regulation of protein kinases; it is also use to regulate the passage of cations (for example, Ca2+)through ion channels, a mechanism used in retina cells by mammals. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.