Fig. 7: Protonation-dependent transport mechanism of organic anion substrates mediated by OATP.
From: Structure of human drug transporters OATP1B1 and OATP1B3
a Residues within the bicarbonate binding site are shown. Blue line indicates the cation-π interaction. Red lines show hydrogen bonds. Red circle indicates the hydrogen atom responsible for pH-sensitivity. b Proposed structure-based mechanism of transport of organic anion substrates mediated by pH-sensitive OATP proteins. The N- and C-terminal halves of the transporter are colored differently. The anionic moiety of the drug substrate (orange rectangle) is colored red. H indicates a key histidine residue responsible for mediating the protonation. States I and II represent structures from this study.
