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Subunit structure of the acetylcholine receptor from Electrophorus electricus

Conti-Tronconi, Bianca M. and Hunkapiller, Michael W. and Lindstrom, Jon M. and Raftery, Michael A. (1982) Subunit structure of the acetylcholine receptor from Electrophorus electricus. Proceedings of the National Academy of Sciences of the United States of America, 79 (21). pp. 6489-6493. ISSN 0027-8424.

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The amino-terminal amino acid sequences of the four major peptides (Mr 41,000, 50,000, 55,000, and 62,000) present in purified preparations of Electrophorus electricus nicotinic acetylcholine receptor (AcChoR) have been determined for 24 cycles by automated sequence analysis procedures yielding four unique polypeptide sequences. The sequences showed a high degree of similarity, having identical residues in a number of positions ranging between 37% and 50% for specific pairs of subunits. Comparison of the sequences obtained with those of the subunits of similar molecular weight from Torpedo californica AcChoR revealed an even higher degree of homology (from 46% to 71%) for these two highly diverged species. Simultaneous sequence analysis of the amino termini present in native, purified Electrophorus AcChoR showed that these four related sequences were the only ones present and that they occur in a ratio of 2:1:1:1, with the smallest subunit ("α1") being present in two copies. Genealogical analysis suggests that the subunits of both Torpedo and Electrophorus AcChoRs derive from a common ancestral gene, the divergence having occurred early in the evolution of the receptor. This shared ancestry and the very early divergence of the four subunits, as well as the highly conserved structure of the AcChoR complex along animal evolution, suggest that each of the subunits evolved to perform discrete crucial roles in the physiological function of the AcChoR.

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Additional Information:© 1982 by the National Academy of Sciences. Communicated by James Bonner, August 2, 1982. The authors thank John Cooper for expert technical assistance and Laurie Jutzi for her endless patience and expert typing. We also thank Dr. M. Dayhoff for analysis of the amino acid sequences, for construction of genealogical trees, and for informative discussions of the, data. This research was supported by U.S. Public Health Service Grants NS 10294 and GM 06965 and by grants from the Muscular Dystrophy Association of America, the Myasthenia Gravis Foundation (Los Angeles Chapter), the Pew Charitable Trust, and the Weingart Foundation. 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:amino acid sequence; homologous proteins; pentameric complex; receptor evolution
Issue or Number:21
Record Number:CaltechAUTHORS:CONpnas82
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9969
Deposited By: Tony Diaz
Deposited On:01 Apr 2008
Last Modified:03 Oct 2019 00:05

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