Figure 3.

Differences between the behavior of the transmembrane part of the human sweet taste receptor in H₂O vs D₂O. (a) Structure of the TMD of the TAS1R2/TAS1R3 receptor with the probability density (volumetric map) of H₂O (blue) or D₂O (red) molecules within 10 Å of the protein. The conserved water molecules in the X-ray templates are shown in cyan. Water molecules predicted with the software OpenEye52 are shown in licorice representation. (b) Time evolution of the radii of gyration in H₂O (blue) and D₂O (red) from three microsecond time scale simulations (separated by vertical dashed lines) with total mean values as dashed lines, showing that the protein is more compact in D₂O. (c) Snapshot of the transmembrane part of the human sweet taste receptor color-coded that red/blue represents parts more/less rigid in D₂O vs H₂O. The embedding lipid membrane is represented in gray. (d) Difference in root-mean-square fluctuations in MD trajectories. Negative/positive values mean that structures are more/less rigid in D₂O than in H₂O. The red line represents the sum of all residues. INT, intracellular; EXT, extracellular. Adapted from ref (30), copyright 2021 Ben Abu et al. (licensed under CC BY).