Comparison of observed and model-predicted rates of substrate transport across bacterial membranes. The observed concentration of Arg⁺ (red closed circles), Agm²⁺ (blue open circles), or their sum (green squares) in the bacteria culture medium plotted against observation time (Iyer et al., 2002). The curves overlaid on the experimental data represent the calculated Arg⁺ (magenta) and Agm²⁺ (blue) concentrations with the model depicted in Fig. S6. The brown line on top corresponds to the sum of the calculated Arg⁺ and Agm²⁺ concentrations. All calculations were performed as described in the supplemental text at the end of the PDF.