HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Boorman, J. P. B. Articles by Sivilotti, L. G. Search for Related Content PubMed PubMed Citation Articles by Boorman, J. P. B. Articles by Sivilotti, L. G.

Stoichiometry of human recombinant neuronal nicotinic receptors containing the 3 subunit expressed in Xenopus oocytes

James P. B. Boorman, Paul J. Groot-Kormelink and Lucia G. Sivilotti

1. The neuronal nicotinic subunit 3 forms functional receptors when co-expressed with both an and a subunit, such as 3 and
2. We examined the subunit stoichiometry of these 'triplet' 343 receptors by expression in Xenopus oocytes of the 3, 4 and 3 subunits, either in wild-type form or after insertion of a reporter mutation.

3. The mutation chosen was the substitution of a conserved hydrophobic residue in the second transmembrane domain of the subunits (leucine or valine 9Þ) with a hydrophilic threonine. In other ion channels within the nicotinic superfamily, this mutation type consistently increases the potency of agonists. In muscle-type nicotinic receptors, the magnitude of this effect is approximately constant for each mutant subunit incorporated.

4. In 343 receptors, the ACh EC₅₀ was decreased by approximately 17-fold when this mutation was in 3 alone and only by fourfold when 3 alone was mutated. Mutating 4 was equivalent to mutating 3, suggesting that the 'triplet' receptor contains one copy of 3 and two copies each of 3 and 4.

5. Mutating 3 and 3 or 3 and 4 reduced the ACh EC₅₀ further, to values two- to threefold lower than those seen when only 3 or 4 carried the mutation.

6. In 'pair' 34 receptors (known to contain two and three subunits), mutating 4 had a greater effect on the ACh EC₅₀ than mutating 3, in agreement with an : ratio of 2:3 and a constant and independent effect of each copy of the mutation.

7. Our results suggest that 343 neuronal nicotinic receptors contain one copy of 3 and two copies each of 3 and 4 and confirm that in pair 34 receptors the / subunits are present in a 2:3 ratio.

This article has been cited by other articles:

				R. M. Drenan, R. Nashmi, P. Imoukhuede, H. Just, S. McKinney, and H. A. Lester Subcellular Trafficking, Pentameric Assembly, and Subunit Stoichiometry of Neuronal Nicotinic Acetylcholine Receptors Containing Fluorescently Labeled {alpha}6 and 3 Subunits Mol. Pharmacol., January 1, 2008; 73(1): 27 - 41. [Abstract] [Full Text] [PDF]

				M. M. White Pretty Subunits All in a Row: Using Concatenated Subunit Constructs to Force the Expression of Receptors with Defined Subunit Stoichiometry and Spatial Arrangement Mol. Pharmacol., February 1, 2006; 69(2): 407 - 410. [Abstract] [Full Text] [PDF]

				P. V. Plazas, E. Katz, M. E. Gomez-Casati, C. Bouzat, and A. B. Elgoyhen Stoichiometry of the {alpha}9{alpha}10 Nicotinic Cholinergic Receptor J. Neurosci., November 23, 2005; 25(47): 10905 - 10912. [Abstract] [Full Text] [PDF]

				P. J. Groot-Kormelink, S. D. Broadbent, J. P. Boorman, and L. G. Sivilotti Incomplete Incorporation of Tandem Subunits in Recombinant Neuronal Nicotinic Receptors J. Gen. Physiol., June 1, 2004; 123(6): 697 - 708. [Abstract] [Full Text] [PDF]