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. 2014 Apr 29;111(19):E1950–E1959. doi: 10.1073/pnas.1406161111

Fig. 9.

Fig. 9.

Contributions of gating pore residues to the VSD energy landscape. (A) (Left) Position of R1 as it moves near S240 (magenta) in a resting-state cartoon model of the Kv1.2 VSD (47) (resting state, image 32, ref. 47). (Right) Simplified two-state energy diagram showing how increasing the size of the amino acid at position S240 (magenta arrow) prevents the passage of the gating charge, hence stabilizing the resting state relative to active state. (B) (Left) Intermediate-state cartoon model of the Kv1.2 VSD (47) (intermediate state, image 22, ref. 47) showing the positions of R1–R4 and I287. The VSD was rotated 105° about the z axis. (Right) Both size and hydrophobicity of I287 are important to control the VSD main energy barrier. (C) (Left) Active-state cartoon model of the Kv1.2 VSD (47) (active state, image 1, ref. 47) showing the positions of the S4 Arg, I237, F244, and F290. (Right) Increasing the size of the side chain at position F244 (magenta arrow) or increasing the hydrophobicity at position I237 (green arrow) stabilizes the active state. A diagrammatic representation of the role of F290 is shown in Fig. 5F.