FIGURE 2.

Fluorescence-based antiport activities of chimerical proteins in sub-bacterial vesicles. (A) Na⁺ and Li⁺ antiport activities of NhaD1 chimerical proteins. (B) Na⁺ and Li⁺ antiport activities of NhaD2 chimerical proteins. The transport activities were measured in the assay buffer containing 10 mM Tris-MES (pH 8.5), 140 mM choline chloride, 5 mM MgCl₂, 1 μl acridine orange and 60 μg of vesicle protein. The antiporter activity was measured from the dequenching of fluorescence upon the subsequent addition of 10 mM of Na⁺, or Li⁺.