Homology model of the human MCT8 with mapped details of pathogenic mutations and potential localization of the transport channel switching region. A) The top-view on the MCT8 homology model with annotated pathogenic side chain substitutions reveals a detailed insight into the distribution of known mutations. The colour code given to the side chains (sticks) is in accordance with described colour scheme in figure 1. B) This clipped surface top-view visualizes the spatial relation between the wild-type amino acids of mutant positions and the “inside-open” transport channel conformation. Amino acids that are localized at the transition between the open and closed channel part are coloured red (red circle). These residues might be involved in the switching process between the “inside-open” and “outside-open” conformations.