Figure. 3. M2 pore loop variants influence magnesium sensitivity.

(A,B) Composite concentration-response curves for Mg²⁺ inhibition of di-heteromeric receptors in the presence of maximally effective concentrations of agonists (100 μM glutamate and 100 μM glycine) show decreased inhibition in all M2 variants-containing receptors. The data were generated by TEVC recordings on Xenopus oocytes at a holding potential of −60 mV. (C,D) Mg²⁺ current-voltage (I-V) curves for di-heteromeric receptors indicate a decreased Mg²⁺ inhibition of all M2 variant-containing receptors. For the I-V curve, all responses were normalized to those recorded at +30 mV. Fitted and statistical parameters are given in Table 4 and Supp. Table S3.