Molecular modelling of the nicotinic acetylcholine receptor transmembrane region in the open state.

A model of the nicotinic acetylcholine receptor transmem- molecular modelling, concluded that an all-helix bundle was brane region has been constructed which may represent an unlikely structure for the TM. Blanton and Cohen (1994), the channel in its open-state. The positions of helices on the basis of a series of affinity labelling studies using flanking the ion channel match those observed by electron lipophilic photoaffinity probes, have repeatedly produced microscopy and previously reported by others. Residues experimental evidence which they interpret as supporting the labelled, mutated or by other means known to have a orthodox view that the four transmembrane segments of each strong influence on ion flux are each accessible from the subunit are helical. In their experiments M1, M3 and M4 were lumen of the modelled channel. The model provides new labelled and they concluded that for M3 and M4, the labelling insights into our current understanding of the ion channel pattern was compatible with a helical conformation. The structure, and suggests some novel explanations for the pattern obtained for M1, however, could not be assigned results of labelling and mutation studies such as those unambiguously to either a helix or a β-sheet; moreover, the involving ion channel blockers and residue-dependent loop connecting M2 and M3, a region which the classical changes in ion selectivity. helical model does not place in the membrane, was also