TopFluor? PI(4,5)P2 or 1-oleoyl-2-{6-[4-(dipyrrometheneboron difluoride)butanoyl]amino}hexanoyl-sn-glycero-3-phosphoinositol-4,5-bisphosphate (ammonium salt) has been used as a fluorescent lipid in living cells to analyse the cellular localization of phosphatidylinositol (PI) and in the preparation of giant unilamellar vesicles (GUVs) for the ezrin-membrane tethering assays.
Although PI(4,5)P2 is a minor component of cell membranes, it plays a critical role as a substrate for a number of important signaling proteins. PI(4,5)P2 is an intermediate in the IP3/DAG pathway where it is hydrolyzed by phospholipase C to liberate the second messengers, inositol 1,4,5-triphosphate (IP3) and diacylglycerol (DAG). PI(4,5)P2 is also a substrate for PI 3-kinase where it is phosphorylated to PI(3,4,5)P3, an activator of downstream signaling components such as the protein kinase AKT.
