LAUSR

Significance Voltage-dependent ion channels underlie the action potential and other forms of electrical activity in cells. They have been the subjects of much study since Hodgkin and Huxley described the electrical origins of the action potential in 1952. Over the past two decades, structures of voltage-dependent K+, Na+, Ca2+, hyperpolarization-activated cyclic nucleotide–gated and transient receptor potential channels have been determined. The biggest question that remains regarding the structure and mechanism of this entire class of ion channels is: How do the voltage sensors respond to an applied electric field across the membrane? This study presents structures of the Eag voltage-dependent K+ channel in electrically polarized lipid vesicles, using cryo-electron microscopy and showing how the voltage sensors regulate the pore.