P-glycoprotein and ABCG2 (P-gp, ABCB1, ABCG2, BCRP)

P-glycoprotein (ABCB1, MDR1) and ABCG2 (BCRP) are transmembrane proteins of the ATP-binding cassette (ABC) transporter family. Both serve as drug efflux pumps, using ATP hydrolysis to transport a wide range of hydrophobic compounds and xenobiotics across cell membranes, thereby contributing to cellular detoxification and the multidrug resistance phenotype found in various cancers. P-glycoprotein is a full transporter composed of two transmembrane domains and two nucleotide-binding domains, whereas ABCG2 is a half-transporter that functions as a homodimer. Both are expressed in pharmacologically relevant tissues (e.g., intestine, liver, kidney, blood-brain barrier) and play critical roles in drug absorption, distribution, and excretion. Overexpression of these transporters in tumor cells is a major mechanism of resistance to cancer chemotherapy

Other names

MDR1ABCB1multidrug resistance protein 1BCRPbreast cancer resistance proteinCD338

ATP-dependent active efflux of xenobiotic and endogenous substrates across cellular membranes, thereby reducing intracellular drug concentrations and conferring drug resistance