Structural basis of polyspecific drug recognition by MRP2

Multidrug resistance-associated protein 2 (MRP2/ABCC2) is a hepatobiliary ATP-binding cassette transporter that mediates the efflux of endogenous conjugates and many therapeutic agents, yet the basis of its broad ligand specificity remains poorly understood. Here we combine cryo-electron microscopy, ATPase measurements and cell-based transport inhibition assays to define how MRP2 recognizes clinically relevant compounds from distinct chemical classes. We find that chemically diverse ligands occupy overlapping regions of a shared transmembrane cavity but adopt different poses, contact networks and stoichiometries. Ligand recognition is mediated predominantly by a permissive environment complemented by ligand-specific polar interactions, rather than by a single conserved pharmacophore. These findings establish a structural framework for MRP2 polyspecificity and provide insight into hepatobiliary drug disposition and transporter-mediated drug-drug interactions.