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Correlation of polypeptide composition with functional events in acetylcholine receptor-enriched membranes from Torpedo californica

Moore, Hsiao-Ping H. and Hartig, Paul R. and Raftery, Michael A. (1979) Correlation of polypeptide composition with functional events in acetylcholine receptor-enriched membranes from Torpedo californica. Proceedings of the National Academy of Sciences of the United States of America, 76 (12). pp. 6265-6269. ISSN 0027-8424. http://resolver.caltech.edu/CaltechAUTHORS:MOOpnas79

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Abstract

Membrane vesicles containing partially inactivated acetylcholine receptor (AcChoR) channels may produce a full 22Na+ flux response because an excess of channels may exist above the level needed to completely empty the vesicles of ions. Therefore, attempts to use ion flux amplitudes as indicators of AcChoR function may fail due to the presence of these excess AcChoR channels. Random inactivation of variable fractions of AcChoR channels in vesicles by the irreversible binding of the neurotoxin α-bungarotoxin provides a tool for assessing the size of the excess receptor population. Using this approach, we predict that the dependence of the flux response on partial inactivation by α-bungarotoxin will drastically change if an essential AcChoR component is substantially removed from the membranes. Membranes from which Mr 43,000, Mr 90,000, and other polypeptides had been substantially removed by base extraction exhibited a flux response after random inactivation that was indistinguishable from that of untreated membranes. Therefore, those components which are substantially removed by base extraction do not appear to be essential for AcChoR-mediated ion flux.


Item Type:Article
Additional Information:© 1979 by the National Academy of Sciences. Communicated by H.A. Barker, September 27, 1979. The authors thank Drs. N. Davidson and H. Lester for valuable discussions, Steve Blanchard for the nonlinear least squares program we used, Valerie Purvis for illustrations and typing, and John Racs for purified membrane preparations. This research was supported by U.S. Public Health Service Grant NS-10294, by a grant and a fellowship (to P.R.H.) from the Muscular Dystrophy Association of America, and by a grant from the American Heart Association. The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.
Subject Keywords:cation flux; partial inactivation; functional polypeptides
Record Number:CaltechAUTHORS:MOOpnas79
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:MOOpnas79
Alternative URL:http://www.pnas.org/cgi/content/abstract/76/12/6265
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9303
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:12 Dec 2007
Last Modified:14 Nov 2014 19:20

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