Acetylcholine agonistic binding site

Valenzuela F, Weign P, Yguerabide J, Johnson DA. 1994. Transverse distance beween the membrane and the agonist binding sites on the Torpedo acetylcholine receptor a fluorescence study. Biophys J 66 674-682. 

Sullivan D, Cohen JB. 2000. Mapping the agonist binding site of the nicotinic acetylcholine receptor orientation requirements for activation by covalent agonist. J Biol Chem 275 12651-12660. 

Page 80, figure 9.5 Biochemistry, 42 271 -283 (2003), Chiara D.C. et al. Identification of amino acids in the nicotinic acetylcholine receptor agonist binding site and ion channel photolabeled by 4-[(3-trifluo-romethyl)-3H-diazirin-3-yl]benzoylcholine, a novel pho-toaffinity antagonist. Reproduced with permission from publisher and authors. 

Figure 3. Schematic representation of nicotinic acetylcholine receptors. Side (A) and top (B) views ofheteromeric and homomeric nicotinic receptors. Loops A-F forming the agonist binding site of heteromeric receptors and key amino acid residues that have been shown to contribute to the agonist binding are also illustrated in B. Abbreviation ACh, acetylcholine. Reproduced from Ref. 10 with permission of Elsevier. (See page 2 of color insert.)...

Arias, H.R. Localization of agonist and competitive antagonist binding sites on nicotinic acetylcholine receptors. Neurochem. Int. 36 595, 2000. 

Middleton RE, Cohen JB. 1991. Mapping of the acetylcholine binding site of the nicotinic acetylcholine receptor [ H] nicotine as an agonist photoaffinity label. Biochemistry 30 6987-6997. 

Neurotransmission can be blocked pharmacologically at the level of the neuromuscular junction either by an antagonist which competes with acetylcholine at the binding site without activating the receptor or by an agonist which induce an overstimulation of the receptor and thereby a blockade of the transmission. 

Many different receptor types are coupled to G proteins, including receptors for norepinephrine and epinephrine (a- and p-adrenoceptors), 5-hydroxytrypta-mine (serotonin or 5-HT receptors), and muscarinic acetylcholine receptors. Figure 2.1 presents the structure of one of these, the uz-adrenoceptor from the human kidney. All members of this family of G protein-coupled receptors are characterized by having seven membrane-enclosed domains plus extracellular and intracellular loops. The specific binding sites for agonists occur at the extracellular surface, while the interaction with G proteins occurs with the intracellular portions of the receptor. The general term for any chain of events initiated by receptor activation is signal transduction. 

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