Table 2. Key Amino Acid Residues Involved in Ligand Binding Considering Prioritized Clusters Only^a.

^aPrioritized clusters are indicated by colored circles next to the residues: white, 1st enriched OATP1B1; gray, 2nd enriched OATP1B1; blue, 3rd enriched OATP1B1 cluster; dark pink, 1st enriched OATP1B3 cluster; light pink, 2nd enriched OATP1B3 cluster; green, top enriched OATP2B1 cluster. Residues that are reported in the literature to be important for transport activity are highlighted in gray color. Residues that appear to be involved in binding of steroid analogs with a higher frequency in this study (at least 10% of all poses or interaction partners for the respective transporter) are marked in bold font. TMH numbers are annotated in the left column.