Structural themes in ion channels.

The recent crystal structure of the prokaryotic inwardly rectifying potassium channel, KirBac1.1, revealed for the first time the structure of a K+ channel in the closed state plus the location of the activation gate. Comparison of the KirBac1.1 structure with other known ion channels reveals a number of common structural features. These common characteristics include the formation of the ion conduction pathway at the interface between adjacent subunits, non-fixed charges forming part of the ion pathway, electrostatic sinks drawing ions into the channel, helix dipoles, and hydrophobic gates that ultimately prevent ion movement. This review describes in detail common structural themes present in ion channels.