Fig. 6. Models of the outward-inward transition in Glt_Ph and LeuT.

A) The transition from the outward-occluded to inward-occluded state in Glt_Ph involves coordinated movement of the transport domain, which leads to a swap of the “thin” and “thick” gates. Shown for clarity is only the core of Glt_Ph as depicted in Fig. 3. B) The transition from the outward-open to inward-open state of LeuT involves a coordinated tilt of TMs 1b and 6a, inwardly directed movement of EL4, and uncoupled outward movement of TM1a. Color scheme is as in Fig. 3. Blue areas in (B) indicate water pathways.