| Nicotinic acetylcholine receptors (nAChR) are postsynaptic membrane proteins that undergo an extensive conformational change upon binding to acetylcholine, leading to opening of an ion-conducting channel across the plasma membrane. |
Nicotinic receptors, with a molecular mass of 290 kDa, are made up of five subunits, arranged symmetrically around a central pore. Each subunit comprises four transmembrane domains with both the N- and C-terminus located extracellularly.
In vertebrates, nicotinic receptors are broadly classified into two subtypes based on their primary sites of expression: muscle-type nicotinic receptors and neuronal-type nicotinic receptors.
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Figure 1: Schematic representation of the fetal muscle subtype nAChR (a) and the adult muscle subtype nAChR (b).