Identification of basic residues involved in drug export function of human multidrug resistance-associated protein 2.

Abstract

Multidrurg resistance-associated protein 2 (MRP2)/canalicular multispecific organic anion transporter (cMOAT) is involved in the ATP-dependent export of organic anions across the bile canalicular membrane. To identify functional amino acid residues that play essential roles in the substrate transport, each of 13 basic residues around transmembrane regions (TMs) 6-17 were replaced with alanine. Wild type and mutant proteins were expressed in COS-7 cells, and the transport activity was measured as the excretion of glutathione-methylfluorescein. Four mutants, K324A (TM6), K483A (TM9), R1210A (TM16), and R1257A (TM17), showed decreased transport activity, and another mutant, K578A (TM11), showed decreased protein expression. These five mutants were normally delivered to the cell surface similar to the other fully active mutants and wild type MRP2. The importance of TM6, TM16, and TM17 in the transport function of MRP2 is consistent with the previous observation indicating the importance of the corresponding TM1, TM11, and TM12 on P-glycoprotein (Loo, T. W., and Clarke, D. M. (1999) J. Biol. Chem. 274, 35388-35392). Another observation that MRP2 inhibitor, cyclosporine A, failed to inhibit R1230A specifically, indicated the existence of its binding site within TM16.

Statistics

02040'03'05'07'09'11'13'15'17
Citations per Year

206 Citations

Semantic Scholar estimates that this publication has 206 citations based on the available data.

See our FAQ for additional information.

Cite this paper

@article{Ryu2000IdentificationOB, title={Identification of basic residues involved in drug export function of human multidrug resistance-associated protein 2.}, author={S Ryu and Tokao Kawabe and S. Nada and Atsushi Yamaguchi}, journal={The Journal of biological chemistry}, year={2000}, volume={275 50}, pages={39617-24} }