 All 7 combinations of phosphorylated PtdIns have been found in animals, all except PtdIns(3,4,5)"P"3 have been found in plants.PIPKs are today divided into three groups, type I, II and III that share significant sequence homology but differ in the substrate specificities, subcellular localisations and functions.Type 1 are PIPKs that phosphorylate PtdIns4"P" to PtdIns(4,5)"P"2 and are called PtdIns4"P" 5-kinases because they phosphorylate on the D-5 hydroxyl group.