The claudin-15 pore favors permeation of Na⁺, but not Cl⁻. (A and B) Density profile of Na⁺ and Cl⁻ ions along the permeation pathway of claudin-15 pore. (C and D) Permeation pathways of Na⁺ and Cl⁻ ions across the pore. The ions are shown in van der Waals representation and are colored by time step with red representing the beginning of their trajectory and blue representing the end. The trajectory of one Na⁺ and one Cl⁻ ion is highlighted (enlarged).