The motions of proteins and lipids in membrane structures are constrained by the 2D nature of the lipid bilayer and by protein interactions within a heterogeneous lipid environment. Many cell functions including signal transduction depend on the motions of proteins within lipids. Our preliminary results from NMR studies of vanadium compounds and their interactions with micelles suggest that at least some of vanadium compounds may be sufficiently lipophilic to insert in the lipid bilayer, an event that may perturb lipid packing as well as lipid lateral diffusion in the plasma membrane. Using information about the distribution of vanadium compounds in reverse micelles from Project 1, will characterize the motions of individual proteins in a membrane with the ultimate goal of understanding how perturbations in membrane lipids can affect compartmentalization of membrane proteins, an emerging mechanism involved in cell signaling. Specifically we will explore whether lipophilic vanadium compounds with insulin-like activity perturb the organization and membrane lipids, driving movement of the insulin receptor into specialized membrane microdomains required for receptor-mediated signaling.