Substrate Recognition/Transport Mechanism of Rat Multidrug Resistance-associated Protein 2.
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Accession number;00A0997678
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| Title;Substrate Recognition/Transport Mechanism of Rat Multidrug Resistance-associated Protein 2. |
| Author;
ITO KOSEI
(Chiba Univ., Fac. of Pharm. Sci.)
SUZUKI HIROSHI
(Chiba Univ., Fac. of Pharm. Sci.)
HORIE TOSHIHARU
(Chiba Univ., Fac. of Pharm. Sci.)
SUGIYAMA YUICHI
(Chiba Univ., Fac. of Pharm. Sci.)
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Journal Title;Xenobiotic Metabolism and Disposition
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Journal Code:X0758A
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ISSN:0916-1139
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VOL.15;NO.Supplement;PAGE.S106-S107(2000)
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| Figure&Table&Reference;FIG.3, TBL.1 |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;Multidrug resistance-associated protein 2(MRP2), along with MRP1, transports glutathione and glucuronide conjugates as well as non-conjugated organic anions. In the present study, we examined the role of charged amino acids in the transmembrane domains of rat Mrp2, conserved among MRP families, by means of site-directed mutagenesis. A single amino acid mutation from Lys to Met at 325(K325M), from Arg to Leu at 586(R586L) and from Asp to Asn at 329(D329N) resulted in a marked reduction in the transport activity of glutathione-S conjugates(2,4-dinitrophenyl-S-glutathione(DNP-SG) and leukotriene C4(LTC4)) without affecting that of the subsequent metabolites of LTC4(LTD4,LTE4 and LTF4) or glucuronide conjugates(17.BETA.-estradiol 17-.BETA.-D-glucuronide(E217.BETA.G) and E3040-glucuronide). In contrast to the reduced affinity for DNP-SG and LTC4, the affinity for E217.BETA.G was increased several-fold in these mutants, suggesting that amino acids at 325 and 586 may play an important role in distinguishing between glutathione and glucuronide conjugates. Furthermore, R1096L aquired the ability to transport TC, which is not transported by Mrp2. Since Mrp3, which transports TC, has a neutral amino acid at 1084 corresponding to this position, the charge-dependence on the transport ability of TC was further investigated in both Mrp2 and Mrp3. In the case of Mrp2, substitution of Arg at 1096 by Lys(R1096K) and Val(R1096V) also resulted in the acquisition of the ability to transport TC. In contrast, substitution of Leu at 1084 of rat Mrp3 by Lys(L1084KMrp3) resulted in the loss of transport activity for both E217.BETA.G and TC, although transport activity for these compounds was unaffected by substitution by Val(L1084VMrp3) or Met(L1084MMrp3).... (author abst.) |
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