Extended Data Fig. 10: Substrate binding and water permeation of SGLT1.

a, For five simulations of SGLT1_con with glucose and two sodium ions initially placed in the glucose and sodium binding sites, the backbone RMSD of SGLT1_con from the cryo-EM structure is plotted over time. b, For five simulations of SGLT1_con with glucose and two sodium ions initially placed in the glucose and sodium binding sites, the heavy atom RMSD of glucose from its initial position is plotted over time. c, A frame from every 200 ns of the 2 μs molecular dynamics simulation (simulation no. 1 in panels (a, b)) shows the position of glucose in the binding pocket (red at t = 0, transitioning to yellow at t = 2 μs). d, Hydrogen bonds between glucose and SGLT1_con binding pocket residues are shown in black lines for simulation no. 1 in panels (a, b). e, Hydrogen bonds between glucose and the SGLT1_con binding pocket residues are shown as the percentage of total simulation time for all simulations in panels (a, b). f, Water occupancy averaged over time for glucose-bound SGLT1_con simulation no. 1 in panels (a, b) (left), and for a 4 μs apo SGLT1_con simulation (right). Water density is shown in dark blue mesh (contoured at 0.0334 water molecules/ų, approximately the bulk density), and glucose is shown in yellow sticks. g, The backbone RMSD of SGLT1_con from the cryo-EM structure (left), and the heavy atom RMSD of glucose from its initial position (right) for five simulations of SGLT1_con with glucose initially placed in the glucose binding site and with no sodium initially placed in the sodium binding sites. Sodium did not enter the sodium binding sites during the timescale of these simulations. h, Uptake activities of SGLT1 mutants. Oocyte-based urea uptake activities with or without inhibitor (200 µM phlorizin, Pz) are compared to the wild-type (WT) transporter (mean ± SEM; n=3 biological replicates). i, Time course of urea uptake by SGLT1 WT and mutants with or without inhibitor phlorizin (Pz). Uptake data were plotted using linear regression (mean ± SEM; n=3 biological replicates).