Figure 5. Summary of the TLR signaling pathway evolution.

Orthologs between different organisms are placed in the same relative position. If orthologs were not found, the ortholog place marked a question mark (?) with a circle. Divergence times of major metazoa groups are presented next to the relevant branches. Our result shows that the complete core pathway known from bilaterians is represented in the sponge Amphimedon queenslandica. The pathway is mostly absent in non-metazoans, Saccharomyces cerevisiae and Monosiga brevicollis. The nematode Caenorhabditis elegans and its relatives Caenorhabditis Brigssae are deficient in several of the pathway components. This may indicate of a functional loss of major components in nematodes.