Identification and functional characterization of a new human kidney-specific H+/organic cation antiporter, kidney-specific multidrug and toxin extrusion 2
Identification and functional characterization of a new human kidney-specific H+/organic cation antiporter, kidney-specific multidrug and toxin extrusion 2
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DOI：
10.1681/asn.2006030205
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发表时间：
2006-08-01
影响因子：
13.6
通讯作者：
Inui, Ken-ichi
中科院分区：
文献类型：
--
作者：
Masuda, Satohiro;Terada, Tomohiro;Inui, Ken-ichi
从人肾组织中分离到一种新的H+/有机阳离子逆向转运蛋白--人肾特异性多药毒素排泄物2(hMATE2-K)。HMATE2-K基因有一个开放阅读框，编码566个氨基酸，与hMATE2、hMATE2-B、hMATE1和大鼠MATE1的同源性分别为94%、82%、52%和52%。逆转录酶-聚合酶链式反应显示hMATE2-K在肾脏中表达，hMATE2-B在除肾脏外的所有组织中均有表达。免疫组织化学分析显示，hMATE2-K和hMATE1定位于近端小管的刷状缘膜。瞬时转染人hMATE2-K基因的HEK293细胞表现出H+梯度依赖性的四乙基铵(TEA)对映体。HMATE2-B基因的导入对hMATE2-K介导的TEA转运无影响。HMATE2-K还转运西咪替丁、1-甲基-4-苯基吡啶(MPP)、普鲁卡因胺、二甲双胍和N-1-甲基烟酰胺。动力学分析表明，TEA、MPP、西咪替丁、二甲双胍和普鲁卡因胺的米氏常数分别为0.83 mm、93.5µM、0.37 mm、1.05 mm和4.10 mm。氯化铵诱导的细胞内酸化显著刺激TEA、MPP、普鲁卡因胺、二甲双胍、N-1-甲基烟酰胺、肌酐、胍、奎尼丁、奎宁、硫胺素和维拉帕米等有机阳离子的hMATE2-K转运。这些结果表明，hMATE2-K是一种新的人类肾脏特异的H+/有机阳离子逆向转运蛋白，它负责阳离子药物跨刷状缘膜的管状分泌。
A cDNA coding a new H+/organic cation antiporter, human kidney-specific multidrug and toxin extrusion 2 (hMATE2-K), has been isolated from the human kidney. The hMATE2-K cDNA had an open reading frame that encodes a 566-amino acid protein, which shows 94, 82, 52, and 52% identity with the hMATE2, hMATE2-B, hMATE1, and rat MATE1, respectively. Reverse transcriptase-PCR revealed that hMATE2-K mRNA but not hMATE2 was expressed predominantly in the kidney, and hMATE2-B was ubiquitously found in all tissues examined except the kidney. The immunohistochemical analyses revealed that the hMATE2-K as well as the hMATE1 was localized at the brush border membranes of the proximal tubules. HEK293 cells that were transiently transfected with the hMATE2-K cDNA but not hMATE2-B exhibited the H+ gradient-dependent antiport of tetraethylammonium (TEA). Transfection of hMATE2-B had no affect on the hMATE2-K-mediated transport of TEA. hMATE2-K also transported cimetidine, 1-methyl-4-phenylpyridinium (MPP), procainamide, metformin, and N-1-methylnicotinamide. Kinetic analyses demonstrated that the Michaelis-Menten constants for the hMATE2-K-mediated transport of TEA, MPP, cimetidine, metformin, and procainamide were 0.83 mM, 93.5 mu M, 0.37 mM, 1.05 mM, and 4.10 mM, respectively. Ammonium chloride-induced intracellular acidification significantly stimulated the hMATE2-K-dependent transport of organic cations such as TEA, MPP, procainamide, metformin, N-1-methylnicotinamide, creatinine, guanidine, quinidine, quinine, thiamine, and verapamil. These results indicate that hMATE2-K is a new human kidney-specific H+/organic cation antiporter that is responsible for the tubular secretion of cationic drugs across the brush border membranes.