A helical segment makes potassium channels go-go.

More than 500 variants in the KCNH2 gene, which encodes the cardiac human ether-a-go-go (hERG) ion channel, have been associated with sudden cardiac death, but only a subset of these variants have been investigated. Matthew D. Perry and colleagues now combine NMR spectroscopy and electrophysiological experiments to explore the functional properties of mutations within an overlooked hERG helix, finding important contributions to channel function.