Fig. 3.

A Branched network model of glucose transport illustrating the effects of the T295M mutation on net influx and efflux at 37 °C. The square and circle symbols represent the same as in Fig. 2A. The right branch to the external vestibule is blocked by the M295 mutation in GLUT1DS and reduces net influx by 50% but without greatly affecting K_m net influx. However, the M295 mutation has a much larger effect on net efflux as slowing efflux leads to an accumulation of glucose within the external vestibule with a tailback that retarded glucose efflux and a reduces the K_m net efflux. B Simulations of the comparative effects of control and mutant glucose net influx and efflux (Cunningham and Naftalin 2013). C Docking studies of GLUT1 showing docking positions of glucose. The effect of the T295M mutation on glucose docking is illustrated in top right panel where the green stick model of glucose is absent from the mutant at the external vestibular tunnel but present in control (red stick) glucose. D Comparison of tunnels in control and M295 mutants. The tunnel between the external solution and vestibule is occluded by the mutant