Fig. 6: Bicarbonate binding pocket and allosteric changes.
From: Structure of human drug transporters OATP1B1 and OATP1B3
a Close-up views of the bicarbonate binding pocket in the OATP1B3 structure. Left panel depicts the EM density (blue mesh) assigned to the bicarbonate molecule. Residues in close contact with the HCO3- anion are displayed as sticks and labeled. b Alignment of human OATP proteins. The sections correspond to the views presented in panel a. Secondary structural elements are depicted and labelled above the sequence. c Ribbon representation of E1S-bound OATP1B1 and bicarbonate-bound OATP1B3 structures superimposed on the N-bundle. (middle) View parallel to the membrane. Dotted frames indicate the zoomed-in regions. (left) Close-up view of the binding pocket with TM7 and TM8 displayed as ribbons. Red arrow indicates the shift in TM8. (right) Close-up view of the interface between the N- and C-terminal bundles showing a shift in ECL4.
