Published Online: 15 APR 2003
Copyright © 2003 by John Wiley & Sons, Inc. All rights reserved.
Encyclopedia of Agrochemicals
How to Cite
Jewess, P. J. 2003. Acetylcholine Receptors. Encyclopedia of Agrochemicals. .
- Published Online: 15 APR 2003
Acetylcholine receptors are protein receptors present on the post-synaptic membrane in the cholinergic nervous system. They specifically bind the neurotransmitter acetylcholine. Upon binding, acetylcholine induces a conformational change that stimulates the opening of cation channels in the nerve membrane, either directly (the nicotinic receptor) or indirectly (the muscarinic receptor), thus, propagating the nerve impulse. The nicotinic acetylcholine receptor (nAChR) is the target for the neonicotinoid insecticides exemplified by imidacloprid, nicotine, the microbial natural product spinosad and insecticides such as cartap based on nereistoxin isolated from a marine worm. The nAChR is one representative of a superfamily of ligand-gated ion-channel receptors having a common evolutionary origin, other examples of which are the glycine, γ-amino butyric acid, glutamate, and 5-hydroxytryptamine receptors. Typically, the nAChR is a transmembrane protein consisting of five subunits of four different types round a central core, which comprises the ion channel through which cations are allowed to pass from one side of the membrane to the other. Two subunits (designated alpha) are responsible for binding acetylcholine. The neonicotinoids act as both agonists in mimicking the action of acetylcholine and antagonists in blocking its action. This disrupts the working of the nervous system and is responsible for the insecticides' toxicity.