Multidrug resistance protein 1a (Mdr1a) (Mdr1a)

Multidrug resistance protein 1a (Mdr1a), also known as ATP-binding cassette sub-family B member 1A (Abcb1a), is a critical transmembrane efflux transporter primarily located in the blood-brain barrier, liver, and intestinal epithelium (NIH, https://pubmed.ncbi.nlm.nih.gov/7909301/). It belongs to the ATP-binding cassette (ABC) transporter family and utilizes ATP hydrolysis to pump a wide range of structurally diverse lipophilic xenobiotics and drugs out of cells (Solvo Biotech, https://www.solvobiotech.com/knowledge-center/transporter-database/mdr1a-b-multidrug-resistance-protein-1a-b-rat). In rodents, Mdr1a is one of two isoforms (along with Mdr1b) that functionally correspond to the single human MDR1 (ABCB1) protein. Mdr1a is a major determinant of drug pharmacokinetics and tissue distribution, particularly in limiting the entry of drugs into the brain and facilitating their excretion (NIH, https://pubmed.ncbi.nlm.nih.gov/8413223/). Overexpression of Mdr1a is a significant factor in the development of multidrug resistance in cancer, as it reduces the effective intracellular concentration of chemotherapeutic agents. Conversely, its absence or inhibition can lead to severe neurotoxicity from otherwise safe drugs and has been linked to the development of spontaneous inflammatory bowel disease in animal models (Taconic Biosciences, https://www.taconic.com/mouse-model/mdr1a-knockout).

Other names

ATP-binding cassette sub-family B member 1AAbcb1aP-glycoprotein 3Pgp3Pgy3Mdr3

ATP-dependent efflux of substrates across the plasma membrane to reduce intracellular drug concentration (NIH, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2651035/).