A minor but important phospholipid with myo-inositol linked through the 1-hydroxyl group to phosphatidic acid. The 4-phosphate (PIP) and 4,5-bisphosphate derivatives (PIP2) are formed and broken down in membranes by the action of specific kinases and phosphatases (futile cycles). A ligand-activated PIP2-specific phosphodiesterase (phospholipase Cγ) breaks down PIP2 to form diacylglycerol, which stimulates protein kinase C, and inositol 1,4,5-trisphosphate (InsP3) which releases calcium from the endoplasmic store. See PI-3-kinases.
Subjects: Chemistry — Medicine and Health.