Fig. 4. Linear uptake of sugars by the OmpL porin. Here we show the dependence of diffusion rates of two sugars on the concentration of OmpL porin in proteoliposomes. The permeation rates of arabinose and glucose were measured using the reconstituted proteoliposome assay with different amounts of OmpL. Proteoliposomes were prepared as described earlier (Nikaido et al., 1991).