The nicotinic acetylcholine receptor controls electrical signalling between nerve and muscle cells by opening and closing a gated, membrane-spanning pore. Here we present an atomic model of the closed pore, obtained by electron microscopy of crystalline postsynaptic membranes ...
The nicotinic acetylcholine receptor controls electrical signalling between nerve and muscle cells by opening and closing a gated, membrane-spanning pore. Here we present an atomic model of the closed pore, obtained by electron microscopy of crystalline postsynaptic membranes. The pore is shaped by an inner ring of 5 alpha-helices, which curve radially to create a tapering path for the ions, and an outer ring of 15 alpha-helices, which coil around each other and shield the inner ring from the lipids. The gate is a constricting hydrophobic girdle at the middle of the lipid bilayer, formed by weak interactions between neighbouring inner helices. When acetylcholine enters the ligand-binding domain, it triggers rotations of the protein chains on opposite sides of the entrance to the pore. These rotations are communicated through the inner helices, and open the pore by breaking the girdle apart.
Related Citations:
Activation of the Nicotinic Acetylcholine Receptor Involves a Switch in Conformation of the Alpha Subunits Unwin, N., Miyazawa, A., Li, J., Fujiyoshi, Y. (2002) J Mol Biol 319: 1165
Nicotinic Acetylcholine Receptor at 9A Resolution Unwin, N. (1993) J Mol Biol 229: 1101
Nicotinic Acetylcholine Receptor at 4.6A Resolution Transverse Tunnels in the Channel Wall. Miyazawa, A., Fujiyoshi, Y., Stowell, M., Unwin, N. (1999) J Mol Biol 288: 765
Organizational Affiliation:
RIKEN Harima Institute, 1-1-1 Kouto, Mikazuki-cho, Sayo, Hyogo 679-5148, Japan.
Download Mendeley
