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Chapter 7,589

Neuronal nicotinic acetylcholine receptors expressed in Xenopus oocytes have a pentameric quaternary structure

Anand, R.; Conroy, W.G.; Schoepfer, R.; Whiting, P.; Lindstrom, J.

Journal of Biological Chemistry 266(17): 11192-11198

1991


ISSN/ISBN: 0021-9258
PMID: 2040627
Accession: 007588622

We have determined the subunit stoichiometry of chicken neuronal nicotinic acetylcholine receptors expressed in Xenopus oocytes by quantitation of the amount of radioactivity in individual subunits of [35S]methionine-labeled receptors. The chicken neuronal nicotinic acetylcholine receptor appears to be a pentamer of two .alpha.4 acetylcholine-binding subunits and three .beta.2 structural subunits. We also show that these expressed receptors bind L-[3H]nicotine with high affinity,are transported to the surface of the oocyte outer membrane, and cosediment on sucrose gradients with acetylcholine receptors isolated from chicken brain. Using this unique and generally applicable method of determining subunit stoichiometry of receptors expressed in oocytes, we obtained the expected (.alpha.1)2.beta.1.gamma.delta. stoichiometry for muscle-type acetylcholine receptors assembled from coexpression of either Torpedo .alpha.1 or human .alpha.1 subunits, with Torpedo .beta.1, .gamma., and .delta. subunits.

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