Nicotinic acetylcholine receptor alpha4beta2 subunit (α4β2 nAChR)

The nicotinic acetylcholine receptor (nAChR) alpha4beta2 subtype (α4β2 nAChR) is a heteropentameric ligand-gated ion channel composed of alpha-4 (α4) and beta-2 (β2) subunits. It is the most abundant nicotinic receptor subtype in the mammalian brain and plays a central role in mediating the effects of nicotine, including its addictive properties. It is highly expressed throughout various brain regions implicated in cognition, reward processing, attention regulation, growth hormone secretion, learning/memory formation, and addiction pathways. The receptor exists in two main stoichiometric configurations: (α4)_3(β2)_2 (low nicotine sensitivity, high calcium permeability) and (α4)_2(β2)_3 (high nicotine sensitivity, low calcium permeability). Smoking cessation agents like varenicline act as partial agonists at α4β2 receptors.

Agonist or partial agonist binding leads to increased Na+ and K+ permeability across neuronal membranes, resulting in neuronal excitation. Antagonists block the receptor and prevent activation.