Ion Channels: Frozen Motion Dispatch

Our understanding of ion permeation through K+ channels, and by extension through other channels, is advancing rapidly. New structural studies, together with computer simulations, have provided profound insights into ion conduction mechanisms. When the crystal structure of the bacterial channel protein KcsA was first solved in 1998 [1], it provided us with our first view of an ion channel at atomic res-olution. The structure, determined at the relatively modest resolution of 3.2 Å, revealed the basic archi-tecture of the channel: an extracellular selectivity filter, a central cavity and an intracellular gate (Figure 1). The importance of KcsA lies in the conservation of this basic pore structure between KcsA and other classes of K+ channels found in a wide range of organisms