Figure 6. Proposed model of the open Na⁺ channel pore for Na_V 1.4.

A, top view. The backbones for P-loops and S6 helices of domains I–IV are shown as green and pink ribbons, respectively. Only the side chains of residues of S6 segments, facing the pore are shown. Residues of domain IV S6 Ile-1575, Phe-1579, and Val-1583 are distinguished as space-filled, while ball and stick representations are shown for the four selectivity filter residues Asp-400, Glu-755, Lys-1237 and Ala-1529 of the domain I–IV P loops. B, side view of the same model with the ribbon of domain II S6 removed. The pore lining residues are shown space-filled as in A.