Fig. 5: Lipid screening for human GLUT1, GLUT3, and GLUT4 mediated uptake and their corresponding zero trans influx kinetics.

a Relative ¹⁴C-d-glucose 30 s uptake for hGLUT1 (red bars), hGLUT3 (light-green bars), hGLUT4 (brown bars), and PfHT1 (mustard bars) and ¹⁴C-d-fructose 2 min uptake for rGLUT5 (purple bars) and ³H-d-xylose 30 s uptake for XylE (lime bars) in proteoliposomes prepared using the different lipid extracts, as in Fig. 1a–d. Non-specific sugar uptake was recorded using protein-free liposomes and subtracted from the recorded specific uptake signal. The uptake was normalized to the brain-fraction-seven lipid extract. Error bars indicate mean ± s.e.m. of n = 3 independent experiments. b Zero trans kinetics of d-glucose uptake for hGLUT1. All data points at their respective d-glucose concentration were measured at 50 s and fitted to a Michaelis–Menten plot with K_M, V_max, and k_cat values subsequently calculated. Error bars indicate mean ± s.e.m. of n = 3 independent experiments. c As in Fig. 5b for hGLUT3. d As in Fig. 5b for hGLUT4. e Comparison of GLUT-specific activity (k_cat/K_M). Black bars represent the calculated specific activity for each GLUT; d-fructose for rGLUT5 and d-glucose for hGLUT1, hGLUT3, and hGLUT4. Data were obtained from previously calculated K_m, and k_cat and error bar represent s.e.m of n = 3 independent experiments.