Phylogenetic analysis of XLG and Gα proteins. Phylogenetic tree (neighbor-joining method) of XLG and Gα proteins of major plant phyla and representatives of five established classes of animal Gαs. Two T. vaginalis Gαs were used as an outgroup. Plant XLG proteins form a distinct subclade within plant Gα group. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1,000 replicates) is shown next to the branches. Bar shows the rate of amino acid substitution. Species used in the analysis: Arabidopsis, Chara braunii, Danio rerio, Homo sapiens, Klebsormidium flaccidum, M. polymorpha, rice (Oryza sativa), Physcomitrella patens, Pseudotsuga menziesii, and T. vaginalis. GPA, G protein alpha; RGA, rice G protein alpha; XM_001330233, not characterized G protein alpha. Gi3, Gvl, Golf, XLas, and Gq are representative proteins of animal G protein alpha subunits.