Alpha-3-beta-4-alpha-5 nicotinic acetylcholine receptor (α5α3β4 nAChR) (α5α3β4 nAChR)

The alpha-3-beta-4-alpha-5 (α5α3β4) nicotinic acetylcholine receptor is a pentameric ligand-gated ion channel composed of CHRNA3, CHRNB4, and CHRNA5 subunits, primarily localized in the autonomic ganglia and the medial habenula-interpeduncular nucleus (MHb-IPN) pathway (Source: UniProt P32297, P30926, P43681). The inclusion of the α5 subunit acts as an accessory component that significantly enhances the calcium permeability and alters the desensitization profile of the receptor compared to the α3β4 subtype (Source: IUPHAR/BPS Guide to Pharmacology). This receptor complex is a critical regulator of the brain's response to nicotine; specifically, the MHb-IPN circuit mediates the aversive effects of high-dose nicotine, effectively acting as a "brake" on consumption (Source: Fowler et al., Nature, 2011). Genetic studies have identified the CHRNA5-A3-B4 gene cluster as a major susceptibility locus for nicotine dependence and lung cancer, with the rs16969968 SNP being a well-documented risk variant (Source: Saccone et al., BioMed Central, 2009). Pharmacologically, the receptor is targeted by smoking cessation agents such as varenicline and cytisine, which act as partial agonists to mitigate withdrawal symptoms (Source: PubChem). However, developing drugs that specifically target this heteromer without affecting other nicotinic subtypes remains a challenge, often leading to side effects related to autonomic nervous system modulation, such as changes in blood pressure and heart rate (Source: NIH/StatPearls).

Other names

CHRNA3/CHRNA5/CHRNB4 complexGanglionic-type nicotinic receptor (alpha-5-containing)Alpha-3-beta-4-alpha-5 nAChRNeuronal acetylcholine receptor subunit alpha-3/alpha-5/beta-4

The receptor functions as a ligand-gated cation channel; upon binding of acetylcholine or nicotine, it undergoes a conformational change to open a pore, allowing the influx of sodium and calcium ions, which leads to cellular depolarization and the activation of downstream signaling pathways or neurotransmitter release.