P-glycoprotein 1 (P-gp) and Breast cancer resistance protein (BCRP) (P-gp and BCRP)

P-glycoprotein 1 (P-gp) and Breast cancer resistance protein (BCRP) are ATP-dependent efflux transporters belonging to the ATP-binding cassette (ABC) transporter superfamily. These proteins are widely expressed on barrier tissues such as the intestines, liver canaliculus, kidney tubules, and the endothelial cells of the blood–brain and blood–retina barriers. Their major role is the active export of numerous structurally diverse foreign substances out of cells, serving as a defense mechanism against toxins. Both transporters play a critical role in limiting the bioavailability and tissue penetration of many pharmaceuticals, thereby contributing to multidrug resistance especially in cancer therapy. Overexpression of either or both proteins in tumors is a known mechanism of chemoresistance. Drugs that inhibit or evade these transporters are actively studied for overcoming drug resistance. Transporter function, genetic variability, and drug interactions all have implications for safety and efficacy in clinical pharmacology.

Other names

Multidrug resistance protein 1MDR1ATP-binding cassette sub-family B member 1ABCB1Cluster of differentiation 243 (CD243)ATP-binding cassette sub-family G member 2ABCG2BCRP

Substrate efflux (reducing intracellular drug concentrations); Drug resistance via reduced drug accumulation; Inhibition of transporter (increasing drug bioavailability or tissue penetration)