Identification of a novel voltage-driven organic anion transporter present at apical membrane of renal proximal tubule
Identification of a novel voltage-driven organic anion transporter present at apical membrane of renal proximal tubule
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DOI：
10.1074/jbc.m303210200
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发表时间：
2003-07-25
影响因子：
4.8
通讯作者：
Endou, H
中科院分区：
文献类型：
--
作者：
Jutabha, P;Kanai, Y;Endou, H
通过在非洲爪蟾卵母细胞中表达克隆的方法，从猪肾皮质中分离到一种新的具有电压驱动的有机阴离子转运特性的转运蛋白。从大小分级的poly（A）（+）RNA构建cDNA文库，并在高钾培养基中筛选对氨基马尿酸（PAH）转运。分离了编码467个氨基酸的肽的1856个碱基对的cDNA，命名为OAT（V）1（电压驱动的有机阴离子转运蛋白1）。预测的OAT（V）1的氨基酸序列与人、大鼠、兔和小鼠钠依赖性磷酸盐协同转运蛋白1（NPT 1）的氨基酸序列具有60-65%的同一性，尽管OAT（V）1不转运磷酸盐。该转运蛋白与有机阴离子转运蛋白家族（OAT家族）的已知成员的同源性约为25- 30%。OAT（V）1介导的PAH转运受膜电位变化的影响。运输是Na+-独立的，并在高浓度的细胞外钾和低浓度的细胞外氯离子增强。在电压钳条件下，细胞外施加PAH诱导表达OAT（V）1的卵母细胞的外向电流。电流显示出陡峭的电压依赖性，与OAT（V）1对PAH的电压驱动转运一致。多环芳烃的运输受到各种有机阴离子的抑制，但不受有机阳离子，表明OAT（V）1的多特异性的阴离子化合物。该转运蛋白定位于肾近端小管的顶膜，与电压驱动的有机阴离子转运蛋白的定位一致。因此，OAT（V）1在通过肾小管上皮细胞尿的顶膜排出药物、外源性物质及其代谢物中起重要作用。
A novel transport protein with the properties of voltage-driven organic anion transport was isolated from pig kidney cortex by expression cloning in Xenopus laevis oocytes. A cDNA library was constructed from size-fractionated poly(A)(+) RNA and screened for p-aminohippurate (PAH) transport in high potassium medium. A 1856-base pair cDNA encoding a 467-amino acid peptide designated as OAT(V)1 (voltage-driven organic anion transporter 1) was isolated. The predicted amino acid sequence of OAT(V)1 exhibited 60-65% identity to those of human, rat, rabbit, and mouse sodium-dependent phosphate cotransporter type 1 (NPT1), although OAT(V)1 did not transport phosphate. The homology of this transporter to known members of the organic anion transporter family (OAT family) was about 25-30%. OAT(V)1-mediated PAH transport was affected by the changes in membrane potential. The transport was Na+-independent and enhanced at high concentrations of extracellular potassium and low concentrations of extracellular chloride. Under the voltage clamp condition, extracellularly applied PAH induced outward currents in oocytes expressing OAT(V)1. The current showed steep voltage dependence, consistent with the voltage-driven transport of PAH by OAT(V)1. The PAH transport was inhibited by various organic anions but not by organic cations, indicating the multispecific nature of OAT(V)1 for anionic compounds. This transport protein is localized at the apical membrane of renal proximal tubule, consistent with the proposed localization of a voltage-driven organic anion transporter. Therefore, it is proposed that OAT(V)1 plays an important role to excrete drugs, xenobiotics, and their metabolites driven by membrane voltage through the apical membrane of the tubular epithelial urine.