Phylogenetic analyses of the mammalian GLUT proteins. (a) Human GLUTs 1-12 and HMIT protein sequences were subject to BLAST searches against the complete genomes of select eukaryotes and prokaryotes. Maximum likelihood phylogeny was inferred from the amino acid sequences of transporter proteins following BLAST searches and ClustalX alignment. Bootstrap supports for groups are given at nodes and tips. The complete phylogenetic tree, with expanded tips showing each individual sequence is shown. (b) Phylogenetic tree illustrating the evolutionary ancestry of five mammalian GLUT classes. Isoforms exhibiting an extended insertion corresponding to the predicted exofacial loop between helices 9 and 10 are indicated.