Figure 1.

(A) Schematic diagram of a supported bilayer laterally confined by barriers. Before application of a field both components are fully mixed and the membrane is of uniform composition. (B) Hypothetical depiction of the molecular reorganization induced by a field in the limit as thermal energy goes to zero. Complete separation of the two components is shown with the negative lipids (shaded dark) gathering toward the anode. The boundary separating the two components has analogies to the Fermi level in quantum mechanical systems. (C) Under normal conditions thermal energy causes a substantial amount of mixing around the boundary, giving rise to a smooth distribution.