Structural basis of MRP2 interactions with substrate and inhibitor.

MRP2 (ABCC2) contributes to multidrug resistance in cancer treatment and plays a key role in liver detoxification. Recent studies on mammalian MRP2 have elucidated its basic structure and regulation via R-domain phosphorylation and displacement, but have not yet explained its substrate preferences or substrate/inhibitor binding modes. We conducted structural and functional studies on human MRP2 with its substrate SN-38G or inhibitor MK-571. Our research provides structural insight into substrate recognition by MRP2 and the positive cooperativity observed in ATP hydrolysis upon SN-38G stimulation, and reveals structural features that contribute to the recognition of glucuronidated substrates. We further identify an MK-571-associated density within the substrate-binding region rather than the nucleotide-binding sites, although its precise binding mode remains unresolved.