Phylogenetic tree of RBR domain segments. A grand alignment of RBR segments from 102 proteins representative of the most populated subgroups was used to create the tree. We used the program SEAVIEW and the tool ATV from the Forester package [71-73]. Each entry is labeled as in Figure 1. Typically, subfamily members cluster nicely together and the phylogenetic relationships within subfamilies are determined with significance. Closer to the root of the tree, the branching becomes increasingly uncertain. Some groups of fungal and protozoan sequences are more heterogeneous and appear at several tree positions. The D. discoideum sequence XP_646567.1 does not appear together with other ARA54 sequences but was assigned to the group 'B (ARA54)' because of the RWD domain in the sequence architecture.