Shape of the membrane from elasticity theory. (A) The solution to Eq. 5 was computed to determine the height of the upper leaflet of the membrane given a deformation near the origin. The membrane–water interfaces of the upper and lower leaflets are represented as two surfaces. We only show the surfaces within a 20 Å radius of the origin. The centers of the surfaces are missing since we assumed that the membrane terminates on a cylindrical helix with a radius of 7.5 Å; full molecular detail is not incorporated at this point. Calculations were performed with parameters found in Table I. (B) The membrane profile for the solution in A is shown along the axis of largest deformation. The cylinder representing the TM segment is shown at the origin (solid black lines), and the surface of the membrane is shown in red. The equilibrium height of the upper leaflet is also pictured (dashed black line) to show that a significant amount of water penetration (blue shade) accompanies membrane bending. (C) The membrane deformation energy increases as the leaflet bends with the deformation reaching a maximum of ∼5 kcal/mol.