Crystal Structure of the Eukaryotic Strong Inward-Rectifier K + Channel Kir2.2 at 3.1 Å Resolution

Abstract

Bio-Diodes: Inward rectifier potassium channels conduct K ⁺ ions into the cell at internal negative membrane voltages, but at internal positive membrane voltages they are blocked by intracellular multivalent ions. These channels control the resting membrane voltage and are required for the healthy function of many electrically excitable cells. Mutations can result in transient paralysis causing, for example, heart problems. Tao et al. (p. 1668 ) now report a 3.1 angstrom resolution structure of the inward rectifier, Kir2.2 from chicken, which has a similar structure to the human equivalent. The combination of observations of conductive and inhibitory ion binding sites with electrophysiological data finally explains the mechanism of action of these long-studied channels and reveals how they maintain their low sensitivity to toxins, as well as provides a basis for the design of therapeutic drugs.