Multidrug resistance protein 1 (P-glycoprotein) (ABCB1)

Multidrug resistance protein 1 (ABCB1), widely known as P-glycoprotein (P-gp), is a member of the ATP-binding cassette (ABC) transporter superfamily that functions as a broad-spectrum efflux pump [1]. It is strategically expressed in barrier tissues such as the intestinal epithelium, the blood-brain barrier, and the canalicular membrane of hepatocytes, where it limits the absorption and enhances the elimination of xenobiotics [2]. In clinical oncology, P-gp is a major driver of multidrug resistance, as it actively removes various chemotherapeutic agents from cancer cells, thereby reducing their efficacy [1, 3]. Beyond cancer, P-gp is a central mediator of drug-drug and herb-drug interactions; for instance, constituents in herbal extracts like St. John's Wort can induce P-gp expression, leading to sub-therapeutic levels of co-administered drugs like digoxin or cyclosporine [4]. Conversely, many phytochemicals such as quercetin or curcumin can inhibit P-gp, potentially increasing the systemic exposure and toxicity of its substrates [4]. Understanding the aggregate effect of these constituents is vital for predicting the pharmacokinetic profile of complex botanical products [3, 4]. Sources: [1] UniProt P08183; [2] NCBI Gene 5243; [3] FDA Drug Interaction Guidelines; [4] PMID: 23116313.

Other names

P-glycoprotein 1P-gpMDR1ATP-binding cassette sub-family B member 1CD243

ATP-dependent efflux pump that transports a wide variety of hydrophobic substrates across cell membranes against a concentration gradient [1, 2].