(IP3) a short-lived biochemical second messenger formed from phospholipid in the cell membrane when a chemical messenger (e.g. a hormone or serotonin) binds to receptors on the cell surface. Inositol triphosphate triggers the rapid release of calcium into the cell fluid, which initiates various cellular processes, such as smooth muscle contraction and the release of glucose, histamine, etc. Inositol triphosphate exists for only a few seconds before being converted to inositol by the action of a sequence of enzymes.
Subjects: Medicine and Health.