Accessible Unlicensed Requires Authentication Published by De Gruyter June 1, 2005

Reconstitution of Transport-Active Multidrug Resistance Protein 2 (MRP2; ABCC2) in Proteoliposomes

Wolfgang Hagmann, Jana Schubert, Jörg König and Dietrich Keppler
From the journal

Abstract

The apical multidrug resistance protein MRP2 (symbol ABCC2) is an ATPdependent export pump for anionic conjugates in polarized cells. MRP2 has only 48% amino acid identity with the paralog MRP1 (ABCC1). In this study we show that purified recombinant MRP2 reconstituted in proteoliposomes is functionally active in substrate transport. The Km values for ATP and LTC4 in the transport by MRP2 in proteoliposomes were 560 M and 450 nM, respectively. This transport function of MRP2 in proteoliposomes was dependent on the amount of MRP2 protein present and was determined to 2.7 pmol min exp.(-1) mg MRP2 exp.(-1) at 100 nM LTC[4]. Transport was competitively inhibited by the quinoline derivative MK571 with 50% inhibition at about 12 M. Our data document the first reconstitution of transportactive purified recombinant MRP2. Binding and immunoprecipitation experiments indicated that MRP2 preferentially associates with the chaperone calnexin, but coreconstitution studies using purified MRP2 and purified calnexin in proteoliposomes suggested that the LTC[4] transport function of MRP2 is not dependent on calnexin. The purified, transportactive MRP2 may serve to identify additional interacting proteins in the apical membrane of polarized cells.

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Published Online: 2005-06-01
Published in Print: 2002-06-26

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