Thes membrane phospholipids, differing only in the fatty acyl components linked to C1 and C2 of the glycerol moiety, also called triphosphoinositides and abbreviated PIP2 or PI-4,5-P2, are important intermediates in a metabolic scheme that generates effectors for a number of metabolic processes. Phosphatidylinositol 4,5-bisphosphate is a precursor to the intracellular messengers inositol 1,4,5-trisphosphate and sn-1,2- diacylglycerol. Phosphatidylinositol 4,5-bisphosphate is an essential cofactor and stimulator of phospholipase D and is a substrate for specific isoforms of phospholipase C. See specific compound Note: The free acid slowly decomposes whereas the sodium salt can be stored cold in chloroform for extended periods. The stearoyl arachidonyl form (i.e., 1’- stearoyl-2’-arachidonoyl-sn-glycerol-3-phospho-1D-myo-inositol 4,5- bisphosphate, shown above) is a form commonly found in mammals. Target(s): [b-adrenergic-receptor] kinase; AMP deaminase; arachidonoyl-diacylglycerol kinase, a specific diacylglycerol kinase; casein kinase I; caspase 8; caspase 9; ER-60 protease; glucose-6-phosphatase; nitric-oxide synthase; phosphatidate cytidylyltransferase; 1-phosphatidylinositol 4-kinase; 1- phosphatidylinositol-4-phosphate 5-kinase, product inhibition; protein kinase C; protein-tyrosine kinase; and sphingomyelin phosphodiesterase, or sphingomyelinase.
