NAChR intracellular domain

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.

The nAChR complexes are ligand-gated channels expressed in skeletal muscles and brain. Five different subunits exist al-9, /il-4, y, 5 and e. These subunits are encoded by different genes on different chromosomes. They are homologous, each with a large N-terminal extracellular domain and four transmembrane regions, with a large intracellular loop between M3 and M4 (Fig. 3). 

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