Nicotinic acetylcholine receptor (muscle-type, adult isoform) (adult nAChR)

The adult muscle-type nicotinic acetylcholine receptor (nAChR) is a pentameric ligand-gated ion channel essential for signaling at the neuromuscular junction. It is composed of four distinct subunits in a stoichiometry of two alpha-1, one beta-1, one delta, and one epsilon subunit ((alpha1)2beta1deltaepsilon), which distinguishes it from the fetal isoform that contains a gamma subunit instead of epsilon (UniProt: P02708, P11230). Upon the binding of two molecules of acetylcholine, the receptor undergoes a conformational change that opens a central pore, allowing the influx of sodium and calcium ions and the efflux of potassium ions (PubMed: 16151244). This ion flow depolarizes the muscle fiber membrane, triggering an action potential that leads to muscle contraction. This receptor is the primary target for neuromuscular blocking agents used during surgery to facilitate intubation and provide muscle relaxation (StatPearls: NBK535431). It is also the central target in the autoimmune disease myasthenia gravis, where pathogenic antibodies reduce the number of functional receptors, leading to muscle weakness (NIH: Myasthenia Gravis).

Other names

Muscle-type nAChRalpha1-beta1-delta-epsilon nAChRCHRNA1-CHRNB1-CHRND-CHRNE complexNMJ nAChRAdult muscle nicotinic receptor

Competitive antagonism of the acetylcholine binding site (non-depolarizing neuromuscular blockers) or prolonged depolarization and desensitization of the receptor (depolarizing neuromuscular blockers).