Functional consequences of AS-associated mutations in KCNJ2. (a) Whole-cell currents in Xenopus oocytes induced by injection of WT KCNJ2, H₂O, G144S and co-expressed WT and G144S KCNJ2. Currents were elicited by 200-ms pulses applied in 20-mV increments to potentials ranging from –150 to –10 mV from a holding potential of –70 mV. G144S mutant subunits failed to form functional channels when expressed alone. Coexpression of WT and G144S KCNJ2 induced small, inwardly rectifying currents. (b) Current voltage relationships for WT KCNJ2 (0.8 ng/oocyte) and coexpressed WT and mutant KCNJ2 (0.8 ng/oocyte of each cRNA). n = 10–18 oocytes/group. Inset, mean current between –70 and –30 mV shown on an expanded scale.