Adenosine triphosphate-dependent transport of anionic conjugates by the rabbit multidrug resistance-associated protein Mrp2 expressed in insect cells

作者：van Aubel RAMH; van Kuijck MA; Koenderink JB; Deen PMT; van Os CH; Russel FGM^*

来源：Molecular Pharmacology, 1998, 53(6): 1062-1067.

The multidrug resistance-associated protein Mrp2 is expressed in liver, kidney, and small intestine and mediates ATP-dependent transport of conjugated organic anions across the apical membrane of epithelial cells. We recently cloned a rabbit cDNA encoding a protein that on basis of highest amino acid homology and tissue distribution was considered to be the rabbit homolog of rat Mrp2. To investigate whether rabbit Mrp2 mediates ATP-dependent transport similar to rat Mrp2, we expressed rabbit Mrp2 in Spodoptera frugiperda (Sf9) cells using recombinant baculovirus. Mrp2 was expressed as an underglycosylated protein in Sf9 cells and to a higher level compared with rabbit liver and renal proximal tubules, Both 17 beta-estradiol-17-beta-D-glucuronide ([H-3]E(2)17 beta G, 50 nM) and [H-3]leukotriene C-4 (3 nM) were taken up by Sf9-Mrp2 membrane vesicles in an ATP-dependent fashion. Uptake of [H-3]E(2)17 beta G. was dependent on the osmolarity of the medium and saturable for ATP (K-m = 623 mu M). Leukotriene C-4, MK571, phenolphthalein glucuronide, and fluorescein-methotrexate were good inhibitors of [H-3]E(2)17 beta G transport. The inhibitory potency of cyclosporin A and methotrexate was moderate,whereas fluorescein, alpha-naphthyl-beta-D-glucuronide, and p-nitrophenyl-beta-D-glucuronide did not inhibit transport. In conclusion, we show direct ATP-dependent transport by recombinant rabbit Mrp2 and provide new data on Mrp2 inhibitor specificity.

• 出版日期1998-6