Phosphatidylinositol is a type of phospholipid, a class of molecules that are essential components of cell membranes. It consists of a glycerol backbone, two fatty acid tails, and a phosphate group linked to an inositol sugar. This structure allows it to play a crucial role in maintaining the integrity and fluidity of cell membranes. In addition to its structural role, phosphatidylinositol is involved in cell signaling. It can be phosphorylated to form various derivatives, such as phosphatidylinositol 4,5-bisphosphate, which are important for processes like cell growth, metabolism, and communication.