Fig. 1.
Cooperation of BSEP, ABCB4 and MRP2 in the canalicular membrane of hepatocytes. BSEP (blue) exports the bile salts, ABCB4 (green) flips phosphatidylcholine to the outer leaflet of the membrane, where it is recruited by bile salts to form mixed micelles. MRP2 (red) maintains the asymmetry in lipid composition by flipping aminophospholipids to the inner leaflet of the membrane.