Journal: The Journal of Biological Chemistry

Article Title: Cyclosporine A sterically inhibits statin transport by solute carrier OATP1B1

doi: 10.1016/j.jbc.2025.108484

Figure Lengend Snippet: Sybody Selection and Characterization and Structure of apo-OATP1B1 with Sb5. A , Sybody 5 binding to apo and cyclosporine A-bound OATP1B1 was characterized by ELISA ( left panel ). Kinetic parameters for Sb5 binding to apo-OATP1B1 were determined using grating-coupled interferometry (GCI) ( right panel ). B , cryo-EM map volume of outward-facing apo-OATP1B1-Sb5 complex and ribbon representation of coordinates, colored by subunit, as indicated. C , residues participating in OATP-Sb5. Left panel , epitope residues are highlighted as magenta spheres with associated residue numbers indicated. Residue bordered by dotted line overlaps with the epitope of Fab 18 (Ciuta et al. , 2023). Y169, indicated by an asterisk , is a histidine in OATP1B3. Right panel , paratope residues are highlighted as yellow spheres with residue numbers indicated. Solid borders indicate residues highlighted in Figure 1 D . D , R103 of Sb5 participates in a hydrogen bond with H115 of OATP1B1, indicated by a dotted line .

Article Snippet: Grating-coupled interferometry (GCI) measurements were made using a Creoptix WAVE system against OATP1B1 immobilized on a streptavidin-coated WAVEchip 4PCP-STA (Creoptix).

Techniques: Selection, Binding Assay, Enzyme-linked Immunosorbent Assay, Cryo-EM Sample Prep, Residue

Journal: The Journal of Biological Chemistry

Article Title: Cyclosporine A sterically inhibits statin transport by solute carrier OATP1B1

doi: 10.1016/j.jbc.2025.108484

Figure Lengend Snippet: Structure of atorvastatin-bound OATP1B1 with Sb5. A , cryo-EM map volume of outward-facing OATP1B1-Sb5 complex bound to atorvastatin and ribbon representation of coordinates, colored by subunit, as indicated. The inset shows the atorvastatin binding site with its corresponding map density, contoured at 3.0σ. B , Ligand-bound structures of OATP1B1 (PDB 8K61 (DCF; white ), PDB 8HNH (simeprevir; green ), PDB 8HND (estrone-3-sulfate; yellow ), PDB 8HNC (bilirubin; magenta )) are aligned with the atorvastatin-bound structure ( orange ). The transparent surface represents the APBS electrostatics surface calculation for atorvastatin-bound OATP1B1, with the major and minor pockets indicated. C , comparison of outward-open atorvastatin binding mode with Autodock Vina predictions. The atorvastatin molecule built into the cryo-EM density is colored in orange , with additional predicted binding poses superimposed in white , green , and yellow . D , low-resolution cryo-EM map of Sb5-free inward-open OATP1B1 bound to atorvastatin. Non-protein density attributed to atorvastatin is colored in magenta .

Article Snippet: Grating-coupled interferometry (GCI) measurements were made using a Creoptix WAVE system against OATP1B1 immobilized on a streptavidin-coated WAVEchip 4PCP-STA (Creoptix).

Techniques: Cryo-EM Sample Prep, Binding Assay, Comparison

Journal: The Journal of Biological Chemistry

Article Title: Cyclosporine A sterically inhibits statin transport by solute carrier OATP1B1

doi: 10.1016/j.jbc.2025.108484

Figure Lengend Snippet: Structure of cyclosporine A-bound OATP1B1 with Sb5. A , cryo-EM map volume of outward-facing OATP1B1-Sb5 complex bound to cyclosporine A and ribbon representation of coordinates, colored by subunit, as indicated. The inset shows the cyclosporine A binding site with its corresponding map density, contoured at 3.0σ. B , structures of atorvastatin- and cyclosporine A-bound OATP1B1 are superimposed, with ligands shown in stick representation and colored as indicated, with major and minor pockets indicated by dotted circles. F356 is shown in stick representation, with its conformational change upon cyclosporine binding indicated by an arrow . C , the binding mode of cyclosporine A as built into the cryo-EM map ( green ) is superimposed with the top prediction from Autodock Vina ( magenta ). D , overlay of outward- and inward-facing structures of OATP1B1 suggest the transport pocket of the outward-occluded conformation is likely too small to accommodate cyclosporine A, preventing transport in either direction.

Article Snippet: Grating-coupled interferometry (GCI) measurements were made using a Creoptix WAVE system against OATP1B1 immobilized on a streptavidin-coated WAVEchip 4PCP-STA (Creoptix).

Techniques: Cryo-EM Sample Prep, Binding Assay

Journal: The Journal of Biological Chemistry

Article Title: Cyclosporine A sterically inhibits statin transport by solute carrier OATP1B1

doi: 10.1016/j.jbc.2025.108484

Figure Lengend Snippet: A model for OATP1B1 statin transport and inhibition by cyclosporine A. Cartoon representation of the OATP1B1 transport cycle and the impacts of atorvastatin and cyclosporine A. In the outward-facing and inward-facing conformations of OATP1B1, the ligand-binding cavity of OATP1B1 is sufficiently large to accommodate atorvastatin or CsA. For atorvastatin, the transition through the outward-occluded state with its reduced-volume cavity, to the inward-open state completes transport across the membrane. Binding of CsA, which can occur to either the outward-open or inward-open state of OATP1B1, does not allow transport because the transition to the outward-occluded state is highly unfavorable, as the smaller cavity of this state is too small to accommodate CsA. Thus, CsA acts as an inhibitor, but not a substrate, of OATP1B1.

Article Snippet: Grating-coupled interferometry (GCI) measurements were made using a Creoptix WAVE system against OATP1B1 immobilized on a streptavidin-coated WAVEchip 4PCP-STA (Creoptix).

Techniques: Inhibition, Ligand Binding Assay, Membrane, Binding Assay