alpha4beta2alpha5 nicotinic acetylcholine receptor (α4β2α5 nAChR)

The alpha4beta2alpha5 (α4β2α5) nicotinic acetylcholine receptor is a heteromeric ligand-gated ion channel and a prominent hybrid subtype found in the mammalian brain. It is typically composed of two α4 subunits, two β2 subunits, and one accessory α5 subunit, which occupies the fifth position in the pentameric ring. While the α5 subunit does not form the primary agonist binding site, its inclusion significantly alters the receptor's biophysical properties, increasing calcium permeability and the rate of desensitization compared to the standard α4β2 receptor. This subtype is particularly critical in the ventral tegmental area (VTA) and other reward-related circuits, where it regulates the sensitivity of dopaminergic neurons to nicotine. Genetic polymorphisms in the CHRNA5 gene, such as the rs16969968 variant, are strongly linked to nicotine dependence and lung cancer risk, making this receptor a key target for smoking cessation therapies. Drugs like varenicline and nicotine act as partial or full agonists at this complex, modulating the reward pathways involved in addiction.

Other names

alpha4beta2alpha5 nAChRalpha5-containing nicotinic receptorCHRNA4/CHRNB2/CHRNA5 complexalpha4beta2alpha5 hybrid nicotinic receptorNicotinic acetylcholine receptor alpha-5 subunit-containing receptor

Agonists or partial agonists bind to the orthosteric sites at the alpha/beta subunit interfaces, while the alpha-5 subunit acts as an accessory component that modulates the channel's calcium permeability and desensitization kinetics.