N-methyl-D-aspartate receptors (NMDARs) play critical roles in both excitatory neurotransmission and synaptic plasticity. NMDARs containing the nonconventional GluN3A subunit have different functional properties compared to receptors comprised of GluN1/GluN2 subunits. Previous studies showed that GluN1/GluN2 receptors are regulated by N-glycosylation; however, limited information is available regarding the role of N-glycosylation in GluN3A-containing NMDARs. Using a combination of microscopy, biochemistry, and electrophysiology in mammalian cell lines and rat hippocampal neurons, we found that two asparagine residues (N203 and N368) in the GluN1 subunit and three asparagine residues (N145, N264 and N275) in the GluN3A subunit are required for surface delivery of GluN3A-containing NMDARs. Furthermore, deglycosylation and lectin-based analysis revealed that GluN3A subunits contain extensively modified N-glycan structures, including hybrid/complex forms of N-glycans. We also found (either using a panel of inhibitors or by studying human fibroblasts derived from patients with a congenital disorder of glycosylation) that N-glycan remodeling is not required for the surface delivery of GluN3A-containing NMDARs. Finally, we found that the surface mobility of GluN3A-containing NMDARs in hippocampal neurons is increased following incubation with 1-deoxymannojirimycin (DMM, an inhibitor of the formation of the hybrid/complex forms of N-glycans) and decreased in the presence of specific lectins. These findings provide new insight regarding the mechanisms by which neurons can regulate NMDAR trafficking and function.

Department of Biomedical Sciences Neuroscience Research Institute Seoul National University College of Medicine Seoul South Korea

Department of Cellular Neurophysiology Institute of Physiology of the Czech Academy of Sciences Prague Czechia Department of Neurochemistry Institute of Experimental Medicine of the Czech Academy of Sciences Prague Czechia

Department of Cellular Neurophysiology Institute of Physiology of the Czech Academy of Sciences Prague Czechia Department of Neurochemistry Institute of Experimental Medicine of the Czech Academy of Sciences Prague Czechia Department of Physiology Faculty of Science Charles University Prague Prague Czechia

Department of Computational Neuroscience Institute of Physiology of the Czech Academy of Sciences Prague Czechia

Department of Neurochemistry Institute of Experimental Medicine of the Czech Academy of Sciences Prague Czechia

Department of Pediatrics and Adolescent Medicine 1st Faculty of Medicine Charles University Prague and General University Hospital Prague Prague Czechia

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