Neuronal nicotinic acetylcholine receptor subunit alpha-2-beta-2 (α2β2 nAChR)

The neuronal nicotinic acetylcholine receptor α2β2 is a heteromeric, pentameric ligand-gated ion channel belonging to the Cys-loop superfamily. This receptor is composed of five subunits arranged around a central water-filled pore, specifically containing alpha-2 (CHRNA2) and beta-2 (CHRNB2) subunits[1][2]. The α2β2 nAChR forms a functional heteropentameric receptor complex with high calcium permeability among other cations[5][8]. Structurally, each subunit contains four transmembrane segments (M1-M4), with a large extracellular N-terminal domain and a small C-terminal region[1][2]. The ligand-binding sites are located at the interfaces between the α and β subunits in the extracellular N-terminal domain. The second transmembrane segment (M2) from each subunit primarily forms the wall of the ionic pore, which is mainly permeable to sodium and calcium ions[2]. The α2 subunit contains characteristic adjacent cysteine residues (Cys192 and Cys193) in the extracellular domain that define it as an alpha subunit[1][2]. The receptor functions as a pentameric complex that can be activated by endogenous acetylcholine or exogenous ligands like nicotine, opening the cation channel upon ligand binding[2]. The α2β2 nAChR plays important roles in modulating neurotransmitter release, cell excitability, neuronal integration, and networking throughout the central nervous system[6]. These receptors are involved in various physiological functions and are considered important therapeutic targets[4]. The β2 subunit is an indispensable component for many nAChR-mediated functions and contributes significantly to the physiological and pharmacological properties of the receptor, including desensitization, inward rectification, and functional characteristics[2]. The receptor exhibits typical nAChR conformational states including closed (resting), open (activated), and desensitized states[1]. The kinetics of these transitions, ionic conductance, and pharmacological properties depend on the specific subunit composition. The α2β2 subtype represents one of the many possible heteromeric combinations that contribute to the functional diversity of neuronal nicotinic receptors in the mammalian brain[1].

Other names

α2β2 nicotinic receptoralpha-2-beta-2 nAChRCHRNA2-CHRNB2 receptor complexNeuronal acetylcholine receptor α2β2 subtype

Ligand-gated ion channel activation; Cation influx (primarily sodium and calcium); Membrane depolarization; Downstream calcium signaling cascades; Modulation of neuronal excitability