Structure of the Acetylcholine-Gated Channel

Summary

The structure of the acetylcholine-gated channel, trapped in open as well as closed states, has been analysed by electron crystallographic methods. The channel has large vestibules extending from the membrane which shape the acetylcholine-binding pockets and facilitate selective transport of cations across a narrow membrane-spanning pore. When acetylcholine enters these pockets it triggers a concerted conformational change that opens the pore by destabilizing a gate in the middle of the membrane made by a ring of pore-lining α-helical segments. The alternative ‘open’ configuration of pore-lining segments reshapes the lumen and creates new surfaces, allowing the ions to pass through. Recent results, at nearly 4 Å resolution, have defined more precisely the structure of the pore and the design of the vestibular entrances.