Ligand binding domains, nAChR

The nAChRs contain multiple binding domains that can accommodate different classes of endogenous and exogenous ligands. The nAChR ligand binding domain consists of seven loops (A-G) spaced on the protein chains of the a and... 

The refined 4 A resolution electron microscopy structure of the hetero-pentameric musde-type, (al)2jSyd uAChR has elegantly illustrated considerable structural similarity of L-AChBP with the nAChR ligand-binding domain. Therefore, L-AChBP is now considered a structural and functional surrogate of the nAChRs. 

Figure 2.1 Diagram of nicotinic acetylcholine receptor (nAChR) structure. A top view of (A) an a7 nAChR and (B) a p2 nAChR shows that homomeric and heteromeric classes of nAChRs are both pentameric in structure. Each subunit is made up of four transmembrane domains with the M2 domain making up the ion pore. (C) A side view of the four transmembrane regions shows the N terminus, C terminus, and large M3-M4 intracellular loop that make up each nAChR subunit. The extracellular loops are available for binding to ligands and the intracellular loop is available for regulation of the nAChR by intracellular signaling proteins.

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