Figure 3. Functional analysis using oocytes

Two electrode voltage clamp experiments were performed on oocytes injected with L522P-hkNBCe1 cRNA (A,C,E) or wt-hkNBCe1 cRNA (B,D,F) as previously reported in the literature [7]. Oocytes were clamped at -60 mV while the bath was continuously perfused with the indicated salt solutions. HCO₃^- solutions were pH 7.5 at room temperature and 5% CO₂ so that [HCO₃^-] is 33 mM. Na⁺ was replaced isotonically with choline. Only hkNBCe1 displays currents with HCO₃^- addition or Na⁺ removal in HCO₃^- solution. A,B: Currents at -60 mV. C,D: The current-voltage (IV) relationships. For IV curves, raw currents were subtracted from the baseline current measured in non-HCO₃^- solution (square, peak HCO₃^- current; circles, steady-state HCO₃^- current; upright triangle, peak 0Na⁺/HCO₃^- current; inverted triangles, steady-state 0Na⁺/HCO₃^- current). E,F: The results of immunostaining with a kNBCe1 specific antibody (α333) as previously described [7]. Membrane staining is obvious for wt-hkNBCe1 (F) but not for L522P (E). Water controls were negative (not shown).