NMDAR ^V618G –BK coupling efficiency is unaltered in symmetrical Mg²⁺solutions. (A) Location of residues involved in the coordination of the Mg²⁺ block: N616 in GluN1, and N615 and V618G in GluN2B (PDB accession no. 7SAA) (Chou et al., 2022). (B) Normalized I-V graphs obtained from quantification of whole-cell currents recorded from HEK293T cells co-expressing BK with GluN1/GluN2B^V618G in the absence (red symbols) or presence of symmetrical Mg²⁺ (blue symbols). (C) Normalized charge-voltage (Q-V) relationships for NMDAR inward currents from the experiments described in B. (D) Functional coupling between BK and NMDAR estimated as Q_outward/Q_inward relationships versus voltage.