Identification of the apical membrane-targeting signal of the multidrug resistance-associated protein 2 (MRP2/MOAT).
The human canalicular multispecific organic anion transporter (cMOAT), known as the multidrug resistance-associated protein 2 (MRP2), is normally expressed in the liver and to a lesser extent in the kidney proximal tubules. In these tissues MRP2 specifically localizes to the apical membrane. The construction of MRP2 fused to the green fluorescent protein, and subsequent site-directed mutagenesis enabled the identification of a targeting signal in MRP2 that is responsible for its apical localization in polarized cells. The specific apical localization of MRP2 is due to a C-terminal tail that is not present in the basolaterally targeted MRP1. Deletion of three amino acids from the C-terminal of MRP2 (DeltaMRP2) causes the protein to be localized predominantly in the basolateral membrane in polarized Madin-Darby canine kidney cells. Interestingly, MRP2 expressed in a mouse leukemia cell line (L1210 cells) predominantly accumulates intracellularly with minimal cell membrane localization. In contrast, DeltaMRP2 was shown to predominantly localize in the cell membrane in L1210 cells. Increased transport of 2,4-dinitrophenyl glutathione from L1210 cells expressing DeltaMRP2 showed that the re-targeted protein retains its normal function.
Molecular Genetics Group, Division of Molecular Medicine, John Curtin School of Medical Research, Australian National University, Canberra ACT 0200, Australia.
M J
MJ
Harris
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M
Kuwano
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M
Webb
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D018435:ATP Binding Cassette Transporter, Subfamily B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D027321:Anion Transport Proteins; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D004285:Dogs; D018432:Drug Resistance, Multiple; D019450:Genes, MDR; D005978:Glutathione / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D049452:Green Fluorescent Proteins; D006801:Humans; D007668:Kidney; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D007700:Kinetics; D007939:Leukemia L1210 / Q000473:pathology; D008099:Liver / Q000378:metabolism; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics; D026901:Membrane Transport Proteins; D051379:Mice; D008969:Molecular Sequence Data; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014162:Transfection; D014407:Tumor Cells, Cultured
D018435:ATP Binding Cassette Transporter, Subfamily B; D027321:Anion Transport Proteins; D002352:Carrier Proteins; D005978:Glutathione; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011993:Recombinant Fusion Proteins; C000715087:ABCC2 protein, human; C030190:S-(2,4-dinitrophenyl)glutathione; C421109:multidrug resistance-associated protein 1