NACHO Engages N-Glycosylation ER Chaperone Pathways for α7 Nicotinic Receptor Assembly

The α7 nicotinic acetylcholine receptor participates in diverse aspects of brain physiology and disease. Neurons tightly control α7 assembly, which relies upon NACHO, an endoplasmic reticulum (ER)-localized integral membrane protein. By constructing α7 chimeras and mutants, we find that NACHO requires the α7 ectodomain to promote receptor assembly and surface trafficking. Also critical are two amino acids in the α7 second transmembrane domain. NACHO-mediated assembly is independent and separable from that induced by cholinergic ligands or RIC-3 protein, the latter of which acts on the large α7 intracellular loop. Proteomics indicates that NACHO associates with the ER oligosaccharyltransferase machinery and with calnexin. Accordingly, NACHO-mediated effects on α7 assembly and channel function require N-glycosylation and calnexin chaperone activity. These studies identify ER pathways that mediate α7 assembly by NACHO and provide insights into novel pharmacological strategies for these crucial nicotinic receptors. [Display omitted] •NACHO mediates functional assembly of transmembrane domains within the α7 nAChR•Two amino acids in the TM2 domain of α7 are critical for NACHO-mediated assembly•NACHO associates with the oligosaccharyltransferase machinery and with calnexin•Neuronal α7 function requires N-glycosylation and calnexin chaperone activity Kweon et al. find that NACHO protein is essential for assembly of transmembrane domains within the α7 nicotinic acetylcholine receptor. NACHO associates with the endoplasmic reticulum oligosaccharyltransferase machinery and with calnexin. Accordingly, functional expression of neuronal α7 receptors requires N-glycosylation and calnexin chaperone activity.