ATP-binding cassette sub-family B member 1 (ABCB1) (ABCB1)

ATP-binding cassette sub-family B member 1 (ABCB1), widely known as P-glycoprotein 1 (P-gp) or multidrug resistance protein 1 (MDR1), is an essential plasma membrane protein that acts as an ATP-dependent efflux pump (UniProt P08183). It is primarily expressed in barrier and excretory tissues, including the intestinal epithelium, liver canalicular membrane, renal proximal tubules, and the endothelial cells of the blood-brain barrier (PubMed: 25700201). Its physiological role is to protect the body by pumping out potentially harmful xenobiotics and toxic metabolites into the gut lumen, bile, or urine (StatPearls). In clinical oncology, ABCB1 is a major driver of multidrug resistance (MDR) because it actively extrudes various chemotherapeutic agents, such as taxanes and vinca alkaloids, from tumor cells, thereby lowering their intracellular concentration and efficacy (NIH/NCI). Additionally, ABCB1 plays a critical role in pharmacokinetics; many common medications are substrates or inhibitors of this transporter, leading to significant drug-drug interactions (PubMed: 30121151). While efforts to therapeutically inhibit ABCB1 to sensitize cancers to treatment have faced clinical challenges, it remains a vital target for understanding drug disposition and toxicity (Wikipedia).

Other names

P-glycoprotein 1Multidrug resistance protein 1MDR1CD243GP170P-gp

ATP-dependent efflux pump that translocates substrates across the cell membrane against a concentration gradient to the extracellular space (UniProt P08183).