Phosphatidylcholine translocator ABCB4 (ABCB4)

Phosphatidylcholine translocator ABCB4 is a member of the ATP-binding cassette (ABC) transporter family, specifically mediating the ATP-dependent translocation ("flop") of phosphatidylcholine from the inner to the outer leaflet of the canalicular membrane in hepatocytes, thereby facilitating the secretion of phosphatidylcholine into bile. This activity is essential for normal bile formation and protects biliary epithelium from detergent effects of bile salts. Structural studies reveal conformational states where lipid binding, recruitment, and extrusion are coupled to ATP binding and hydrolysis. Mutations in ABCB4 cause inherited cholestatic disorders, and its function can be inhibited by drugs such as posaconazole, leading to adverse hepatic effects[3][7]. ABCB4 activity is crucial for lipid homeostasis and liver health.

Other names

ATP-binding cassette sub-family B member 4MDR3Multidrug resistance protein 3

Inhibition of phosphatidylcholine translocation (e.g., by binding and blocking lipid recruitment or extrusion)[3]