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| NIGEL UNWIN | |
| Ion Channels and Dendritic Spines |
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Ion channels play a central role in the rapid transmission of electrical signals throughout the nervous system. We are interested in finding out how these membrane proteins work, using electron microscopy to analyse their structures trapped in different physiological states.
Our research currently focuses on the nicotinic acetylcholine receptor - the transmitter-gated ion channel at the junction between nerve and muscle cells. Images of isolated Torpedo postsynaptic membranes have now revealed the three-dimensional structure of this channel to a resolution of about 4Å. |
Freeze-trapping, combined with imaging experiments are providing a mechanistic picture of how binding of acetylcholine opens the channel. Transmitter-gated ion channels are concentrated at chemical synapses - the places where nerve cells make connections and communicate with each other. These connections are found at spines protruding from the dendrites of nerve cells. Using light-optical imaging of intact tissue, we found that the spines of Purkinje cells have a preference to trace short-pitch helical paths. The purpose of this three-dimensional organisation may be to maximise the opportunity of different spines to interact with different axons. |
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| Miyazawa, A., Fujiyoshi, Y. & Unwin, N. (2003) Structure and gating mechanism of the acetylcholine receptor pore. Nature 423, 949-955. Unwin, N. (2005) O’Brien, J. & Unwin, N. (2006) |
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