Fig. 2: Functional characterization of LysP.

a [³H]L-lysine counterflow uptake by reconstituted LysP. Blue shows transport into proteoliposomes containing LysP and red shows transport into liposomes with no LysP (control). Error bars represent the mean ± standard error of the mean (s.e.m). of three independent experiments for proteoliposomes and two for liposomes. b IC₅₀ curves for the competitive inhibition of [³H]-L-lysine uptake by external cold L-lysine (blue) and L-arginine (green) in LysP proteoliposomes preloaded with 1 mM of the respective amino acids. Uptake activity was normalized after subtraction of non-specific uptake, estimated from protein-free liposomes. Error bars represent the mean ± s.e.m. from three independent experiments. c Inhibition of [³H]L-lysine transport into proteoliposomes reconstituted with LysP. The inhibition was carried out in the presence of 10 mM of the different cold substrates. Error bars represent the mean ± s.e.m. of four independent experiments. d Binding of L-lysine and L-arginine to LysP by microscale thermophoresis (MST). Error bars represent the mean ± s.e.m. of three independent experiments. e Binding of thialysine to LysP by MST. Error bars represent the mean ± s.e.m. of three independent experiments. f pH gradient test: uptake of ³[H]L-lysine in reconstituted liposomes with LysP (proteoliposomes) and without LysP (control liposomes) at pH 4 inside and outside (red) and at pH 7 inside and pH 4 outside (blue). Error bars represent the mean ± s.e.m. of four independent experiments. g Sodium gradient test: uptake of ³[H]L-lysine in reconstituted liposomes with LysP (proteoliposome) with (blue) and without the addition of 50 mM NaCl (red). Error bars represent the mean ± s.e.m. of four independent experiments. Source data for Fig. 2 are provided in the Source Data file.