Membrane specific electrostatic potentials [15, 41] (ESPs) on the molecular surface of cholesterol. The assignment of partial charges is based on force fields: (a) AMBER(RESP), (b) AMBER(bcc), (c) CHARMM, and (d) GROMACS. Shown are color-coded ESPs (dark red: −5 ; dark blue: +5) mapped onto the molecular surface of the average structure revealed from 5 ns of MD simulation. Standard or slightly increased van der Waals radii form the basis of molecular surface calculation.