Figure 6.

Phylogenetic tree of the Rho family. Representative species for which fairly complete sets of Rho proteins are available have been selected. Besides the 15 D.discoideum (Dd) Rho proteins, we also retrieved for this study sequences of six Rho proteins from E.histolytica (Eh), six from S.cerevisiae (Sc), 13 from A.thaliana (At), five from C.elegans (Ce), seven from D.melanogaster (Dm), six from G.gallus (Gg) and 19 from H.sapiens (Hs). Amino acid sequences of the GTPase core were aligned and a bootstrapped unrooted phylogenetic tree was constructed using the neighbour joining method as described in Materials and Methods. A consensus tree obtained with the parsimony method yielded comparable results. The innermost node of each branch supported by >50% bootstraps has been marked with a circle. The scale bar indicates 10% divergence. Dictyostelium Rho-related proteins are highlighted in black. Well-defined subfamilies have been marked on the right, using dashed lines to include closely related members not clearly supported by bootstrapping. Except for DdRac1a/1b/1c, RacF1/F2 and, to a lesser extent, RacB and RacA, which can be grouped in the Rac subfamily, neither of the additional Dictyostelium Rho-related proteins fall into any of the other subfamilies. Note that the DdRacA GTPase domain is more closely related to Rac proteins than to RhoBTB proteins, where RacA actually belongs. The closest relatives of DdRacC and DdRacE are EhRacC and AtU88402, respectively.