During the formation of vesicles that occurs in membrane traffic, membrane lipids undergo dramatic structural rearrangements. Thus, the cell must, somehow, overcome the energy barrier of the required lipid structural changes. One way of reducing the energy barrier is to modify the membrane lipid composition, making such membranes conducive to vesicle formation. In fact, lipid-modifying enzymes such as phospholipase D and phosphatidylinositol phosphate kinase have been implicated in membrane traffic. My research investigates the role of such enzymes in regulating rates of membrane traffic, particularly the internalization of the epidermal growth factor receptor, and aims to elucidate the mechanistic basis of such regulation.