Homology of the human PCFT to various transporters and 3D modeled structure of PCFT based on the crystal structure of the glycerol-3-phosphate transporter. The bioinformatics analysis performed here is given in great detail in Document S1. (A) A section of the multiple sequence alignment created by MUSCLE (residues 95-136 according to the human PCFT sequence; see bioinformatic methodology in Document S1). The human PCFT appears in the first line. Note the remarkable degree of conservation at this segment and especially human PCFT residue R113 that is absolutely conserved in many transporters from bacteria to man. This figure was prepared with JALVIEW³¹  and edited with GNU Image Manipulation Program (GIMP; http://www.gimp.org). (B-D) The 3D modeled structure of human PCFT viewed from the extracellular face. TM helices are presented in ribbon and residue side chains are shown in sticks and colored by element (carbon in gray, oxygen in red, and nitrogen in blue). (B) TM1, TM3, TM4, and TM6 in the vicinity of R113 and R114. (C) The D109-R114 short loop between TM2 (not shown) and TM3 (see panel A). (D) Overall view of the model. The 4 TM regions surrounding the conserved loop appear on the right bottom corner of the figure. Molecular graphics images were produced using the Chimera package from the Resource for Biocomputing, Visualization, and Informatics at the University of California, San Francisco (supported by National Institutes of Health P41 RR-01 081).