Figure 1: Homology model of the human B0AT1 transporter. Legend: The homology model was created using the Swiss-Model web server (54). Subsequently, the substrate and Na+ ion were reintroduced at the original coordinates. The figure was generated using PyMOL (DeLano Scientific). A: the view from the side (extracellular side top). B: the transporter from top. Helix 1 is depicted in yellow, and helix 6 is depicted in blue. Putative regions with ?-sheet conformation are also depicted in yellow. The backbone of the protein is highlighted. Residues found to be mutated in Hartnup disorder individuals and mentioned in the text are shown in full size. From Bröer S. Apical Transporters for Neutral Amino Acids: Physiology and Pathophysiology. Physiology 23: 95-103, 2008