Ligand interaction areas. Close-up of putative ligand interaction areas of ABCB1 (Panel A) and ABCC5 (Panel B). The view is a cross-section of the transporters perpendicular to the membrane. The oval shaped object with the text "Verapamil" (Panel A) indicates where Verapamil binding may take place. TMHs are shown as blue Cα traces. Color coding of displayed residues: Carbon: White; Hydrogen: Grey; Oxygen: Red; Nitrogen: Blue. Panel A: Residues Leu65 (TMH1) , Ile306 (TMH5) , Ile340 (TMH6) [25, 30] and Phe343 (TMH6)  have been shown to interact with ligands in site directed mutagenesis studies. Panel B: Corresponding residues in ABCC5 are Gln190 (TMH1), Val410 (TMH5), Asn441 (TMH6) and Thr444 (TMH6) respectively.