Cation leak in X laevis oocytes expressing wild-type or mutant RhAG. (A) RhAG expression levels in X laevis oocytes were assessed by immunoblotting using an antibody to C-terminal RhAG. A proportion of aggregate was detected, as indicated. (B) Li⁺ uptake (as a surrogate for Na⁺) was measured 2 days after injection. The result is a representative experiment of 4 repeats. Data are means of 7 oocytes plus or minus SEM. (C) Intracellular sodium and potassium ion concentrations were measured 2 days after injection. Data, expressed in micromolar per gram of dry weight (μmol/g d.w.), are the mean values for 3 separate experiments plus or minus SEM. (D) Intracellular sodium and potassium ion concentrations were measured 3 days after injection. Data, expressed in micromolar per gram of dry weight, are the means of triplicate measurements for each condition plus or minus SEM. The result is a continuation of one of the experiments shown in panel C.