Figure 7.

Homology models of PCFT in the inward and outward conformations highlighting the Phe-392, Asp-109, Gly-305 and Ser-196 residues. Homology models of human PCFT in the outward-open (blue) and inward-open (green) conformations were generated based upon the crystal structures of the bovine and rat GLUT5 fructose transporters as described previously (18). Phe-392, located in the endofacial region of the 11th transmembrane segment (highlighted) points into the aqueous translocation pathway in the inward-open conformation and shifts further into the pathway in the outward-open conformation. Asp-109 in the second transmembrane segment is in proximity to Phe-392. Ser-196 in the fifth transmembrane segment is located in close proximity to Gly-305 in the exofacial region of the eighth transmembrane segment. A, planar view. B, a view into the protein from the extracellular compartment. C, a view into the protein from the intracellular compartment.