Figure 3.

(a) View of a hypothetical K_v-type K⁺ channel from the extracellular side of the membrane, showing the central pore-forming region, S5-P-S6, modeled by the structure of KcsA, surrounded by a voltage-gating domain of unknown structure, composed of S1-S4. Reproduced with permission from [25]. (b) Diagram of a typical K⁺ channel, showing the outward movement of the voltage-sensing transmembrane segment S4 concomitant with channel opening. Reproduced with permission from [26].