Multidrug resistance-associated protein 5 (MRP5) (MRP5)

Multidrug resistance-associated protein 5 (MRP5), also known as ABCC5, is a member of the ATP-binding cassette (ABC) transporter superfamily that functions as an ATP-dependent efflux pump [1, 2]. It is ubiquitously expressed in human tissues, with particularly high levels in the brain, muscle, and heart, where it mediates the transport of a wide range of organic anions, including cyclic nucleotides (cGMP and cAMP), glutamate conjugates, and heme [5, 9, 10]. In clinical oncology, MRP5 is a key driver of multidrug resistance (MDR) because it actively extrudes various chemotherapeutic agents, such as thiopurines (6-mercaptopurine, 6-thioguanine) and fluoropyrimidines (5-fluorouracil metabolites), from tumor cells, thereby decreasing their intracellular concentration and therapeutic effect [3, 8, 11]. Additionally, MRP5 plays a role in the disposition of antiviral nucleoside analogs like adefovir and tenofovir [1, 4]. Beyond drug resistance, it is involved in physiological processes such as glutamatergic signaling, adipogenesis, and insulin sensitivity, and its dysregulation has been linked to conditions ranging from cardiovascular disease to neurological disorders [9, 10, 12].

Other names

ABCC5ABC33MOAT-CSABCpABC11SMRPATP-binding cassette subfamily C member 5

ATP-dependent efflux transporter that reduces intracellular drug concentrations by pumping substrates across the plasma membrane [1, 8, 9].