Sodium-binding sites are conserved in ASCT2. (A and B) Na1 (A)- and Na2 (B)-binding sites for Na⁺ after 8 ns of MD simulation. (C) Representative traces for the distance between the T382 α carbon and the Na⁺ ion in the Na2 site as a function of time for the alanine- and Na1-bound transporter (red), and in the absence of alanine (black and green). (D) Time evolution of the distance between D473(Oδ2) and the cation in the Na1 site in the absence of occupied Na2 (black), as well as in the absence of both Na2 and alanine (red). (E) Distances calculated from an 8-ns MD simulation between D386(Oδ2) and Na3. The colors indicate distances calculated from the same simulation in the three different subunits (black, chain A; red, chain B; green, chain C). (F) Predicted Na3-binding site at the end of a 10-ns simulation.