FIGURE 2.

ATP-dependent MRP1-mediated transport of endogenous and xenobiotic solutes. The diagram illustrates the diversity of molecules effluxed by MRP1 across the plasma membrane in an ATP-dependent fashion. Included are representative examples of the endogenous/physiological substrates, both proposed and demonstrated, effluxed by MRP1 such as lipid-derived effectors and mediators of cell signaling (and their receptors) implicated in the etiology and progression of multiple human diseases. The best characterized physiologic substrate of MRP1, viz. LTC₄, is highlighted, and only in this case is the dependence of transport on ATP depicted. Also shown are the multiple and complex roles of GSH, both as a transported solute and as a stimulant of the transport of other solutes by MRP1. The ATP dependence of MRP1-mediated transport of these molecules is not depicted due to space constraints but is understood. EP1–4 refers to the four subtypes of PGE₂ receptors. Abbreviations: GS-DHN, GS-1,4-dihydroxy-nonene; GS-HNEA, GS-4-hydroxy-2-nonenoic acid; BF, bioflavonoid; LTCS, LTC₄ synthase; LTD₄, leukotriene D₄; LTE₄, leukotriene E₄; COA, conjugated organic anion; dPGJ₂, 15-deoxy-Δ^(12,14) PGJ₂; S1PR1–5, S1P receptors 1–5; UCOA, unconjugated organic anion; VRP, verapamil; 'X', hydrophobic xenobiotic or drug.