Muscle-type nicotinic acetylcholine receptor (alpha-1, beta-1, delta, epsilon) (nAChR)

The muscle-type nicotinic acetylcholine receptor (nAChR) is a pentameric ligand-gated ion channel located at the postsynaptic membrane of the neuromuscular junction. In adults, the receptor is composed of two alpha-1, one beta-1, one delta, and one epsilon subunit, a configuration that distinguishes it from the fetal form (UniProt). Its primary biological function is to mediate fast excitatory neurotransmission; upon the binding of acetylcholine released from the motor neuron, the channel opens to allow the influx of sodium and calcium ions and the efflux of potassium ions (StatPearls). This ion flow causes membrane depolarization, which triggers an action potential and subsequent muscle contraction (PubMed). The receptor is a major therapeutic target for neuromuscular blocking agents used in clinical anesthesia to provide muscle relaxation for surgery and intubation (StatPearls). Clinically, it is also the primary target of autoimmune destruction in Myasthenia Gravis, where autoantibodies reduce the number of functional receptors, leading to muscle weakness and fatigue (NIH). Additionally, mutations in the genes encoding these subunits can lead to congenital myasthenic syndromes (PubMed). Pharmacological modulation of this receptor is essential for managing surgical patients and treating certain neuromuscular disorders.

Other names

Adult muscle-type nicotinic acetylcholine receptorNeuromuscular nicotinic acetylcholine receptorCHRNA1/CHRNB1/CHRND/CHRNE complexNicotinic acetylcholine receptor alpha-1 beta-1 delta epsilonMuscle nAChR

The receptor acts as a ligand-gated ion channel that opens in response to acetylcholine binding, allowing cation influx and membrane depolarization. Drugs targeting this receptor include non-depolarizing competitive antagonists that block acetylcholine binding and depolarizing agonists that cause persistent activation and subsequent desensitization of the receptor.