Chapter

The Single Ion Channel

Alan J. McComas

in Galvani’s Spark

Published in print August 2011 | ISBN: 9780199751754
Published online September 2011 | e-ISBN: 9780199897094 | DOI: http://dx.doi.org/10.1093/acprof:oso/9780199751754.003.0019
The Single Ion Channel

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A “gating” current, predicted by the Hodgkin-Huxley equations twenty years earlier, is finally detected in the squid giant axon. Soon after, Bert Sakmann and Erwin Neher develop a patch clamp method for recording the opening and closing of single ionic channels in a membrane. They apply their method to the acetylcholine receptor, while Shosaku Numa and his colleagues determine the amino acid sequence of the receptor by means of DNA analysis. Finally, the 3-dimensional outline of the acetylcholine receptor is derived by Nigel Unwin and Chikashi Toyoshima using X-ray diffraction and electron microscopy. Numa’s group turn their attention to the voltage-gated sodium channel and show that it is formed from four repeats of a basic unit, each of which has six membrane-spanning segments. Although the amino acids likely to form the “gates” are identified, the operating mechanism of the gates remains unknown.

Keywords: gating current; Bert Sakmann; Erwin Neher; patch clamp; Shosaku Numa; aminoacid sequence; acetylcholine receptor; sodium channel

Chapter.  4460 words.  Illustrated.

Subjects: Neuroscience

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