Evolution of mitochondrial localization for the branched-chain-amino-acid aminotransferases family. (a) Gene tree generated by PhyML  for vertebrates, yeast and outgroup species that speciated before duplication events. Bootstrap values (100 repetitions) are shown on the internal branches. Proteins surrounded by an oval are localized to mitochondria; loss of the mitochondrial localization is marked by a cross. (b) Clustal W  alignment of the amino-terminal region of orthologs. The predicted targeting sequences are highlighted in blue. Abbreviations: hs. Homo sapiens; mm, Mus musculus; dm, Drosophila melanogaster; dr, Dano rerio; lm, L. major; sc, S. cerevisiae.