(Science: biochemistry) A phosphatidic acid combined with inositol found in biomembranes and a precursor to certain cellular signals. Sometimes referred to as inositide.
It is a very important minor phospholipid in eukaryotes, involved in signal transduction processes. Contains 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).
signal sensitive phospholipase C enzymes remove the inositol moiety, in particular from 1,4,5 trisphosphate (PIP2) as inositol 1,4,5 triphosphate (Ins P3: iP3). Both the diacyl glycerol and products act as second messengers.