FIG. 3.

Citrate uptake driven by artificial gradients. Artificial gradients were imposed across RSO membranes prepared from E. coli TOP10 expressing CimHbs as described in Materials and Methods. [1,5-¹⁴C]citrate uptake was measured at pH 6.0 in the presence of both the ΔpH and ΔΨ components (○), only ΔpH (▿), and only ΔΨ (□).