Fig. 5.

Model for ligand-gated transport in EcFadL. In the closed state of the channel (Left), the α-amino group of the N terminus interacts with the carboxyl group of D348 and the side chain of F3 forms part of the high-affinity binding site. Substrate (green square) binding in the high-affinity site causes a conformational change of the N terminus. The resulting displacement of F3 from the binding site leads to substrate release and opens the channel (Right). The substrate subsequently moves through the lateral gap into the outer leaflet of the OM (7).