P-glycoprotein, Breast cancer resistance protein, Multidrug resistance-associated protein 1

P-glycoprotein (ABCB1), breast cancer resistance protein (ABCG2/BCRP), and multidrug resistance-associated protein 1 (ABCC1/MRP1) are major ATP-binding cassette (ABC) transporters that mediate the active, energy-dependent export of structurally diverse drugs and other xenobiotics across cell membranes[1][2][4]. They play key roles in limiting drug bioavailability and distribution, conferring multidrug resistance to cancer chemotherapy, and regulating tissue permeability (e.g., at the blood–brain barrier, intestines, liver, kidney, and placenta)[2][4]. Overexpression of these proteins in tumor cells is a primary mechanism for clinical drug resistance[2][4]. All have broad substrate specificity, transporting a wide array of endogenous compounds (hormones, lipids) and exogenous drugs, often acting synergistically or redundantly[2][4].

Other names

MDR1ABCB1multidrug resistance protein 1PgpABCG2breast cancer resistance proteinABCC1multidrug resistance-associated protein 1

ATP-dependent efflux of drugs and xenobiotics, lowering intracellular concentrations and conferring multidrug resistance; Drug antagonists/blockers (e.g., verapamil) inhibit the transporter, increasing sensitivity to drugs or altering ADME (absorption, distribution, metabolism, excretion) profiles.