The high turnover Drosophila multidrug resistance-associated protein shares the biochemical features of its human orthologues |
| |
Authors: | Fló ra Szeri,Attila Iliá s,Viola Pomozi,É va Bakos |
| |
Affiliation: | a Institute of Enzymology, Hungarian Academy of Sciences, Budapest, P.O. Box 7, H-1518, Hungary b Department of Zoology, University of Hawaii - Manoa, Honolulu, HI, USA |
| |
Abstract: | DMRP, an ABC transporter encoded by the dMRP/CG6214 gene, is the Drosophila melanogaster orthologue of the “long” human multidrug resistance-associated proteins (MRP1/ABCC1, MRP2/ABCC2, MRP3/ABCC3, MRP6/ABCC6, and MRP7/ABCC10). In order to provide a detailed biochemical characterisation we expressed DMRP in Sf9 insect cell membranes. We demonstrated DMRP as a functional orthologue of its human counterparts capable of transporting several human MRP substrates like β-estradiol 17-β-d-glucuronide, leukotriene C4, calcein, fluo3 and carboxydichlorofluorescein. Unexpectedly, we found DMRP to exhibit an extremely high turnover rate for the substrate transport as compared to its human orthologues. Furthermore, DMRP showed remarkably high basal ATPase activity (68-75 nmol Pi/mg membrane protein/min), which could be further stimulated by probenecid and the glutathione conjugate of N-ethylmaleimide. Surprisingly, this high level basal ATPase activity was inhibited by the transported substrates. We discussed this phenomenon in the light of a potential endogenous substrate (or activator) present in the Sf9 membrane. |
| |
Keywords: | ABC, ATP-binding cassette BB, benzbromarone cAMP, 3&prime -5&prime -cyclic adenosine mono-phosphate CDCF, carboxydichlorofluorescein CFTR, cystic fibrosis transmembrane conductance regulator DMRP, Drosophila multidrug resistance-associated protein E217βDG, β-estradiol 17-β- smallcaps" >d-glucuronide GSH, reduced glutathione IM, indomethacin LTC4, leukotriene C4 MRP, multidrug resistance-associated protein NBD, nucleotide binding domain NEM-GS, N-ethylmaleimide glutathione conjugate PB, probenecid SUR, sulfonylurea receptor Sf9, Spodoptera frugiperda ovarian cells TMD, transmembrane domain Vi, orthovanadate |
本文献已被 ScienceDirect 等数据库收录! |
|