The role of membrane thickness in charged protein-lipid interactions

► Simulations reveal ion-induced defect mechanism for charge movement in membranes. ► Translocation free energies are linearly dependent on bilayer thickness. ► The cost of burying arginine in a thin membrane is small, consistent with experiments. ► Pores form in thinner bilayers, solubility-diffusion predicted in thicker bilayers. ► Small pKa shifts observed, but with deprotonation predicted in thick bilayers.