Figure 2

A phylogenetic tree of Mep, AMT and Rh-like proteins. Rh and AMT/Mep proteins are found in bacteria, archaebacteria and eukaryotes. The amino acid sequence alignment was created using the program ClustalW, and phylogenetic analysis was done using the program PAUP 4.0b4a. Highly variable amino- and carboxy-terminal sequences were removed before analysis. Only one archaebacterial sequence (Mj, Methanococchus janaschii) and those prokaryotic sequences that have been analyzed for ammonia transport have been included: Ec, Escherichia coli; Sy, Synechocystis sp.; Ac, Azorhizobium caulinodans; Av, Azotobacter vinelandii; Ab, Azospirillum brasilense; Re, Rhizobium etli; Cg, Corynebacterium glutamicum. With the exception of human (Hs, Homo sapiens), slime mold (Dd, Dictyostelium discoideum), marine sponge (Gc, Geodia cydonium), and zebrafish (Danio rerio), only eukaryotic sequences from fully sequenced organisms (Dm, Drosophila melanogaster (fruit fly); Ce, Caenorhabditis elegans (nematode); At, Arabidopsis thaliana (plant); Sc, Saccharomyces cerevisiae (yeast)) have been included.