Figure 3

Illustration of a model for inferring the protein architecture of most recent common ancestors (MRCAs). Based on the distribution patterns of SRLKs and SRLCKs in a kinase-domain tree, gene duplication/speciation and gene fusion/fission events were inferred. (A) Protein architecture of SRLKs (represented by filled triangles), SRLCKs (represented by open triangles), and SRLPs. (B) When the two leaves on bifurcating branches are of the same architecture (either SRLK or SRLCK), a duplication or speciation event is inferred. (C) When the two leaves are of different architectures (one SRLK and one SRLCK), the ancestral architectures at the inner nodes were inferred by the leaf architectures of the deeper branch as illustrated.