Fig. 2.

The sequential movements of positively charged residues (red spheres) upon depolarization. The highly conserved hydrophobic residue (F²³³) in the gating charge transfer center (formed by F²³³, E²³⁶, and D²⁵⁹) is shown as a green sphere. The other key negatively charged residues (E¹⁸³, E²²⁶, E²³⁶, and D²⁵⁹) are shown as blue spheres. The gating transitions are associated with the predominant translational/rotational movements of the S4 helix along the relatively fixed S3 helix, sliding around 13 Å normal to membrane.