Yabuuchi H, Tamai I, Sai Y, Tsuji A
Department of Pharmacobio-Dynamics, Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
Pharm Res. 1998 Mar;15(3):411-6. doi: 10.1023/a:1011920213991.
The purpose of the present study was to investigate the transport of organic monocarboxylic acids mediated by the anion exchanger AE2, which has been already reported to be present at several tissue cell membranes, including intestinal brush border membrane in rabbit.
Membrane transport of organic monocarboxylic acids by AE2 was investigated by transient AE2-gene expression in HEK 293 cells and subsequent uptake studies by the cells.
Functional transfection of AE2 was confirmed by the enhanced 36Cl- efflux from the cells. When preloaded with chloride anion. AE2-transfected cells demonstrated a significantly enhanced [14C]benzoic acid transport activity compared with mock-transfected cells. The AE2-mediated uptake was saturable with kinetic parameters of Km = 0.26 +/- 0.08 mM and Vmax = 6.14 +/- 0.52 nmol/mg protein/3 min and the uptake of [14C]benzoic acid was pH-dependent with a maximal uptake at pH 6.5. AE2-mediated [14C]benzoic acid uptake was inhibited by Cl-, HCO3-, and DIDS. AE2-transfected cells demonstrated significantly enhanced transport activity for nicotinic acid, propionic acid, butyric acid, and valproic acid as well as benzoic acid compared with mock-transfected cells.
AE2 is functionally involved in the anion antiport for organic monocarboxylic acids as well as inorganic anions and is supposed to play a partial role in the intestinal transport of organic acids.
本研究旨在调查由阴离子交换蛋白AE2介导的有机一元羧酸的转运，此前已有报道称AE2存在于多种组织细胞膜上，包括兔的肠刷状缘膜。
通过在HEK 293细胞中瞬时表达AE2基因并随后进行细胞摄取研究，来调查AE2介导的有机一元羧酸的膜转运。
通过细胞中增强的36Cl-外流证实了AE2的功能性转染。当预先加载氯离子时，与mock转染细胞相比，AE2转染细胞表现出显著增强的[14C]苯甲酸转运活性。AE2介导的摄取是可饱和的，动力学参数为Km = 0.26 +/- 0.08 mM和Vmax = 6.14 +/- 0.52 nmol/mg蛋白/3分钟，[14C]苯甲酸的摄取依赖于pH，在pH 6.5时摄取最大。AE2介导的[14C]苯甲酸摄取受到Cl-、HCO3-和DIDS的抑制。与mock转染细胞相比，AE2转染细胞对烟酸、丙酸、丁酸和丙戊酸以及苯甲酸的转运活性显著增强。
AE2在功能上参与了有机一元羧酸以及无机阴离子的阴离子反向转运，并且推测在有机酸的肠道转运中起部分作用。
