Multidrug resistance protein 1 (ABCB1) (ABCB1)

Multidrug resistance protein 1 (ABCB1), widely known as P-glycoprotein (P-gp), is a prominent ATP-dependent efflux pump belonging to the ATP-binding cassette (ABC) transporter superfamily [UniProt: P08183]. It is strategically expressed in physiological barriers such as the blood-brain barrier, intestinal epithelium, hepatocytes, and renal proximal tubules, where it functions to limit the entry of potentially toxic xenobiotics and facilitate their excretion [PubMed: 25130544]. In clinical medicine, P-gp is a major determinant of drug disposition, affecting the absorption, distribution, and elimination of a diverse array of therapeutic agents [StatPearls: NBK556137]. Its overexpression in malignant cells is a primary mechanism of multidrug resistance, as it effectively lowers the intracellular concentration of various chemotherapeutic drugs, thereby compromising treatment outcomes [PubMed: 30103369]. Furthermore, P-gp is a critical site for drug-drug interactions; the co-administration of P-gp inhibitors or inducers can significantly alter the plasma levels and safety profiles of P-gp substrates like digoxin or loperamide [FDA: Drug Development and Drug Interactions]. Beyond oncology, variations in ABCB1 expression and activity are implicated in the pathogenesis and treatment response of neurological disorders like epilepsy and Alzheimer's disease [PubMed: 23625051]. Understanding the substrate specificity and inhibitory potential of drugs toward P-gp is essential for predicting pharmacokinetic behavior and ensuring patient safety during polypharmacy.

Other names

P-glycoprotein 1P-gpATP-binding cassette sub-family B member 1MDR1CD243 antigen

ATP-dependent efflux of substrates from the cytoplasm or lipid bilayer to the extracellular space [PubMed: 25130544]