Regions A, B, C and D in TIMs. (A) Regions A, B, C and D in the TIMs of the 20 species in our data set. This figure shows the four regions in HsTIM dimer interface (the panel in the upper left corner) and their aligned residues in the TIMs from the other 19 organisms. Residues are colored with the same scheme as Figure 1. The water molecules (blue spheres) shown in each panel are the interfacial water. Please note that these figures are not the actual interfaces (except the one of Homo sapiens TIM), but just the part that are aligned with HsTIM dimer interface, though the water molecules are actual interfacial water.