Structure and Anticipatory Movements of the S6 Gate in K _v Channels

Potassium channels are a diverse family of membrane proteins that in humans are encoded by 75 distinct genes. The ion conduction pores in these channels are well conserved, supporting remarkable ion throughput rates (10⁶–10⁷ s⁻¹) in the face of exquisite selectivity for their namesake ion. Although some potassium channels are always open, more typically the ion conduction pore changes conformation between open and closed states in response to a biological stimulus. In the voltage-activated (K_v) variety of potassium channels, the opening and closing of the channel is driven by movements in the voltage sensing domains, a topic that continues to sustain an energized discussion (Jiang et al., 2003; Ahern and Horn, 2004; Swartz, 2004; Bezanilla, 2005; Long et al., 2005b). Although the structure and movements of the gate region in K_v channels also has...