Functional significance of aromatic amino acids from three peptide loops of the α7 neuronal nicotinic receptor site investigated by site‐directed mutagenesis

FEBS Letters

Bertrand, Daniel²  Revah, Frédéric¹  Bertrand, Sonia²  Devillers-Thiéry, Anne¹  Changeux, Jean-Pierre¹  Galzi, Jean-Luc¹ 

[1] Neurobiologie moléculaire, Unité de Recherche Associée au Centre National de la Recherche Scientifique D 1284, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France;Département de Physiologie, Centre Médical Universitaire (Faculté de Mèdecine), 1211 Genève 4, Switzerland

关键词: Neuronal nicotinic acetylcholine receptor;    Acetylcholine binding site;    site-directed mutagenesis;    ACh;    acetylcholine;    AChR;    acetylcholine receptor;    DHβE;    dihydro-β-erythroidine;    DDF;    p-(N;    N) dimethylamino benzene diazonium fluoroborate;   

DOI  :  10.1016/0014-5793(91)80668-S

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Three aromatic amino acids, Tyr⁹², Trp¹⁴⁸ and Tyr¹⁸⁷ belonging to three separate domains of the α7-subunit of neuronal nicotinic acetylcholine receptor were mutated to phenylalanine, and the electrophysiological response of the resulting mutant receptors analyzed in the Xenopus oocyte expression system. All mutations significantly decreased the apparent affinities for acetylcholine and nicotine, and to a lesser extent, those for the competitive antagonists dihydro-β-erythroidine and α-bungarotoxin. Other properties investigated, such as the voltage dependency of the ion response as well as its sensitivity to the open channel blocker QX222, were not significantly changed, indicating that the mutations affected selectively the recognition of cholinergic ligands by the receptor protein. The maximal rates for the rapid desensitization process were slightly modified, suggesting that the contribution of Tyr⁹², Trp¹⁴⁸ and Tyr¹⁸⁷ to the binding area might differ in the various conformations of the nicotinic receptor. Other mutations at nearby positions (S94N, W153F, G151D and G82E) did not affect the properties of the electrophysiological response. These data point to the functional significance of Tyr⁹², Trp¹⁴⁸ and Tyr¹⁸⁷ in the binding of cholinergic ligands and ion channel activation of the nicotinic receptor, thus supporting a multiple loop model [(1990) J. Biol. Chem. 265, 10430–10437] for the ligand binding area.

【 授权许可】

Unknown