ATP-binding cassette subfamily B member 1 and member 11 (ABCB1/ABCB11)

ATP-binding cassette (ABC) transporters ABCB1 (P-glycoprotein/MDR1) and ABCB11 (Bile Salt Export Pump/BSEP) are critical membrane-bound proteins belonging to the ABCB subfamily that utilize ATP hydrolysis to transport substrates across cellular membranes. ABCB1 is a widely expressed multidrug efflux pump found in the blood-brain barrier, intestines, and liver, where it limits the absorption and promotes the excretion of a diverse range of xenobiotics and therapeutic drugs. ABCB11 is primarily localized to the canalicular membrane of hepatocytes and is the principal transporter responsible for the secretion of bile salts into the bile, a critical step in bile formation and dietary fat absorption. While ABCB1 is a major mediator of multidrug resistance in cancer and a key factor in drug pharmacokinetics, ABCB11 is central to hepatobiliary health, with its dysfunction or inhibition leading to severe cholestatic conditions such as progressive familial intrahepatic cholestasis type 2 (PFIC2) and drug-induced liver injury (DILI). The rodent ortholog of human ABCB1 is often referred to as Abcb1a (or Mdr1a), which is frequently studied in conjunction with ABCB11 in preclinical models to assess drug transport and safety.

Other names

ABCB1AMdr1aP-glycoproteinP-gpMDR1BSEPBile salt export pumpPGY4SPGPCD243Multidrug resistance protein 1

ATP-dependent efflux of substrates, competitive inhibition of transport, and positive functional modulation of transporter activity.