Phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3) commonly abbreviated to PIP3 is the product of the class I phosphoinositide 3-kinases (PI 3-kinases) activity on phosphatidylinositol (4,5)-bisphosphate.
The PH domain in a number of proteins binds to PtdIns(3,4,5)P3. Such proteins include Akt/PKB, PDK1, Btk1 and ARNO. The generation of PtdIns(3,4,5)P3 at the plasma membrane upon the activation of class I PI 3-kinases causes these proteins to translocate to the plasma membrane and accordingly affects their activity.
The PH domain allows binding between PtdIns(3,4,5)P3 and G-protein coupled receptor kinases (GRKs). This enhances the binding of the GRK to the plasma membrane.