GluN1/GluN3A receptors display strong redox sensitivity. a Structure of the GluN1 and GluN3A ABDs (PDB 4KCC and 4KCD, respectively). Cysteines involved in endogenous redox-sensitive disulfide bridges are highlighted (sulfur atoms shown in yellow). The central cartoon illustrates domain organization in GluN1/GluN3A receptors; NTD, N-terminal domain; ABD, agonist-binding domain; TMD, transmembrane domain; CTD, C-terminal domain. b Effect of TCEP treatment (5 mM, 20 min) on wild-type and mutant GluN1/GluN3A receptors expressed in HEK 293 cells. Glycine was applied at 100 µM. Each trace comes from a separate cell. c Quantification of tail currents observed upon washout of glycine on wild-type and mutant GluN1/GluN3A receptors. Inset indicates current tags used for quantification. n.s. P = 0.125 and 0.337, Student’s t-test (n = 4–9). Note that non-treated receptors containing wild-type GluN3A subunits do not exhibit tail currents. Data are mean ± SEM. d Effect of reduced glutathione (GSH, 50 mM for 20 min) on wild-type GluN1/GluN3A receptors expressed in HEK293 cells. Glycine was applied at 100 µM. e Effect of TCEP treatment (5 mM, 20 min) on wild-type GluN1/GluN3A receptors expressed in Xenopus oocytes. The pair of current traces corresponds to responses before and after TCEP treatment on the same cell. Glycine was applied at 100 µM