Figure 1.

Anion selectivity of NBCe1. A) NBCe1 expressed in Xenopus oocytes produces electrogenic outward currents in response to HCO₃⁻, but not other anions. Recording was done while oocytes were exposed to different anions (25 mM for each). B) Zero current voltage (E_rev) versus anion radius. Note that HCO₃⁻ has a large effective radius, but produces a current. The molecular or effective radius (in Å) is 1.81 Cl⁻, 1.89 NO₃⁻, 1.96 Br⁻, 2.13 SCN⁻, 2.20 I⁻ and 2.8 HCO₃⁻. n = 6 for each.