Navigating regulated cell excitation Voltage-gated sodium (Na v ) channels respond to a change in voltage potential by allowing sodium ions to move into cells, thus initiating electrical signaling. Mutations in Na v channels cause neurological and cardiovascular disorders, making the channels important therapeutic targets. Shen et al. determined a high-resolution structure of a Na v channel from the American cockroach by electron microscopy. The structure affords insight into voltage sensing and ion permeability and provides a foundation for understanding function and disease mechanism of Na v and the related Ca v ion channels. Science , this issue p. eaal4326