α6-Containing Nicotinic Acetylcholine Receptor Reconstitution Involves Mechanistically Distinct Accessory Components

Acetylcholine gates a large family of nicotinic receptor cation channels that control neuronal excitation and neurotransmitter release. These receptors are key targets for neuropsychiatric disorders; however, difficulties in expressing nicotinic acetylcholine (nACh) receptors hamper elaboration of their pharmacology and obscure elucidation of their biological functions. Particularly intriguing are alpha 6-containing nACh receptors, which mediate nicotine-induced dopamine release in striatum-nucleus accumbens. Using genome-wide cDNA screening, we identify three accessory proteins, beta-anchoring and -regulatory protein (BARP), lysosomal-associated membrane protein 5 (LAMP5), and SULT2B1, that complement the nACh receptor chaperone NACHO to reconstitute alpha 6 beta 2 beta 3 channel function. Whereas NACHO mediates alpha 6 beta 2 beta 3 assembly, BARP primarily enhances channel gating and LAMP5 and SULT2B1 promote receptor surface trafficking. BARP knockout mice show perturbations in presynaptic striatal nACh receptors that are consistent with BARP modulation of receptor desensitization. These studies unravel the molecular complexity of alpha 6 beta 2 beta 3 biogenesis and enable physiological studies of this crucial neuropharmacological target.