Figure 5. Replacing the N-terminal domain of NBCn1-B with the N-terminal domain of NBCe1-A.

A, chimeric transporter e1(Nt)/n1. B, (I–V) relationships obtained from oocytes expressing e1(Nt)/n1 in the absence (○) and presence (•) of HCO₃⁻–CO₂ (n = 7). C, representative recordings of pH_i and V_m in an oocyte expressing e1(Nt)/n1. The pH_i recovery from a CO₂-induced acidification (arrow) without affecting membrane potentials (arrowhead) are hallmarks of electroneutral Na⁺–HCO₃⁻ transport. A substantial hyperpolarization caused by Na⁺ removal is due to an associated Na⁺ conductance. One of four experiments.