Identification of the apical membrane-targeting signal of the multidrug resistance-associated protein 2 (MRP2/cMOAT)
Identification of the apical membrane-targeting signal of the multidrug resistance-associated protein 2 (MRP2/cMOAT)
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DOI：
10.1074/jbc.m010566200
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发表时间：
2001-06-15
影响因子：
4.8
通讯作者：
Board, PG
中科院分区：
文献类型：
--
作者：
Harris, MJ;Kuwano, M;Board, PG
人小管多特异性有机阴离子转运蛋白（cMOAT），被称为多药耐药相关蛋白2 (MRP2)，通常在肝脏中表达，少量在肾近端小管中表达。在这些组织中，MRP2特异性定位于顶膜。MRP2的构建与绿色荧光蛋白融合，随后的定点突变使MRP2中的靶向信号得以识别，该信号负责其在极化细胞中的顶端定位。MRP2的特定根尖定位是由于c端尾部不存在于基底侧靶向MRP1中。MRP2的c端缺失三个氨基酸（Delta MRP2）导致该蛋白主要定位于极化的Madin-Darby犬肾细胞的基底外膜。有趣的是，MRP2在小鼠白血病细胞系（L1210细胞）中的表达主要积聚在细胞内，很少有细胞膜定位。相反，Delta MRP2在L1210细胞中主要定位于细胞膜。表达Delta MRP2的L1210细胞中2,4-二硝基苯基谷胱甘肽的运输增加，表明重靶向蛋白保持其正常功能。
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 (Delta MRP2) 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, Delta MRP2 was shown to predominantly localize in the cell membrane in L1210 cells. Increased transport of 2,4-dinitrophenyl glutathione from L1210 cells expressing Delta MRP2 showed that the re-targeted protein retains its normal function.