Comparison of the Na binding sites in the LeuT_Aa (dark grey) and dDaT (light grey) crystal structures and the GlyT2 model (colored helices).

Crystallographic Na⁺ from the LeuT_Aa Na1 and Na2 sites are shown as dark grey spheres. The three modeled Na⁺ in GlyT2 are colored purple. Na⁺ occupies the Na1 and Na2 sites, and the proposed Na’ site of GlYT2. The substrate glycine is shown in CPK spacefill.