Effects of mutations on P-Glt _Ph . (a) Close-up view of S279 mutation. The model and density map are from Data S2 refined in C3 (PDB accession no. 7RCP). A water molecule replacing Na1 and coordinated by D405N is emphasized as a red ball. Hydrogen bonds are displayed using hbond in ChimeraX. (b) Cartoon representation of a protomer viewed in the membrane plane (left) and from the extracellular space (right), showing S279E points away from the transport domain.