Cryo-EM Captures the Dynamics of Ion Channel Opening.

In this issue of Cell, Hite and MacKinnon (2017) report the open conformation structure of Slo2.2, a neuronal Na+ -activated K+ channel. More importantly, 3D classification of electron cryomicroscopy (cryo-EM) images allows visualization of the structural transition that occurs as the open probability of individual channels increases with added sodium.