Consensus phylogenetic tree of selected Ras superfamily members rooted with outliers. The 165 proteins selected after careful individual analyses (see Figs. S1–S5) of species-trees and gene-trees covering the Ras superfamily sequences, plus three sequences (human mitochondrial, plant chloroplast, and bacterial) of representative Elongation factor Tu (a remote homologue of Ras superfamily) used to root the tree, were aligned to the G-domain (see main text). The tree is a consensus of more than 126,769 sampled trees with their associated probabilities. The numbers in brackets indicate stable groups; *, absent in Plants and alveolates; **, absent in alveolates. The founder members are the SRPRB group (1) and the Arf family (2). RABL5 (3; Wu et al., 2002) and RABL3 (4) appear at the basal branches of the Ras family (most likely as founders). This phylogeny proposes SRPRB and the Arf family to be the founder members of the classical Ras superfamily. Underlined names indicate the 22 human sequences. Plants: ARATH (Arabidopsis thaliana); Alveolata: PLAF7 (Plasmodium falciparum); Fungi: SCHPO (Schizosaccharomyces pombe); Yeast: Sce (Saccharomyces cerevisiae); Radiate: Nve (Nematostella vectensis); Worm: CAEEL (Caenorhabditis elegans); Fly: DROME (Drosophila melanogaster); Lanceolet: Bfl (Brachiostoma floridae, protochordata); Ascidian: Cin (Ciona intestinalis, urochordata); Xtr (Xenopus tropicalis); Human (Homo sapiens); and Mouse (Mus musculus).