Characterization of the transport properties of human multidrug resistance protein 7 (MRP7, ABCC10)
Characterization of the transport properties of human multidrug resistance protein 7 (MRP7, ABCC10)
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DOI：
10.1124/mol.63.2.351
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发表时间：
2003-02-01
影响因子：
3.6
通讯作者：
Kruh, GD
中科院分区：
文献类型：
--
作者：
Chen, ZS;Hopper-Borge, E;Kruh, GD
人多药耐药蛋白7（MRP 7，ABCC 10）是最近描述的ATP结合盒蛋白C家族的成员（Cancer Lett 162：181-191，2001）。然而，它的生物化学活性和生理功能尚未确定。在这里，我们报告的调查结果，在体外转运特性的MRP 7使用膜囊泡制备从人胚肾293细胞转染MRP 7表达载体。研究表明，MRP 7的表达与17 β-雌二醇-（17-β-D-葡糖苷酸）（E（2）17 β G）的MgATP依赖性转运特异性相关。E（2）17 β G转运是饱和的，Km和Vmax值分别为57.8 +/- 15 μ M和53.1 +/- 20 pmol/mg/min。相反，使用E（2）17 β G，仅观察到LTC 4转运的适度增强，并且在任何程度上都检测不到MRP家族转运蛋白的其他几种已建立的底物的转运。与MRP 7具有由阴离子和亲脂部分的位点组成的二分底物结合口袋的概念雅阁，E（2）17 β G的转运易受两种两亲物的竞争性抑制，如白三烯C-4（K-i（app），1.5 μ M）、乙醇硫胆酸3-硫酸盐（K-i（app），34.2 μ M）和MK 571（K-i（app），28.5 μ M），和亲脂剂如环孢菌素A（Ki（app），14.4 μ M）。在测试的抑制剂中，LTC 4是最有效的，这与它是泵的底物的可能性一致。MRP 7具有介导缀合物如E（2）17 β G转运的能力的确定表明它是参与解毒的第III阶段（细胞挤出）的亲脂性阴离子转运蛋白。
Human multidrug resistance protein 7 (MRP7, ABCC10) is a recently described member of the C family of ATP binding cassette proteins (Cancer Lett 162:181-191, 2001). However, neither its biochemical activity nor physiological functions have been determined. Here we report the results of investigations of the in vitro transport properties of MRP7 using membrane vesicles prepared from human embryonic kidney 293 cells transfected with MRP7 expression vector. It is shown that expression of MRP7 is specifically associated with the MgATP-dependent transport of 17beta-estradiol-(17-beta-D-glucuronide) (E(2)17betaG). E(2)17betaG transport was saturable, with K-m and V-max values of 57.8 +/- 15 muM and 53.1 +/- 20 pmol/mg/min. By contrast, with E(2)17betaG, only modest enhancement of LTC4 transport was observed and transport of several other established substrates of MRP family transporters was not detectable to any extent. In accord with the notion that MRP7 has a bipartite substrate binding pocket composed of sites for anionic and lipophilic moieties, transport of E(2)17betaG was susceptible to competitive inhibition by both amphiphiles, such as leukotriene C-4 (K-i(app), 1.5 muM), glycolithocholate 3-sulfate (K-i(app), 34.2 muM) and MK571 (K-i(app), 28.5 muM), and lipophilic agents such as cyclosporine A (K-i(app), 14.4 muM). Of the inhibitors tested, LTC4 was the most potent, in agreement with the possibility that it is a substrate of the pump. The determination that MRP7 has the facility for mediating the transport of conjugates such as E(2)17betaG indicates that it is a lipophilic anion transporter involved in phase III (cellular extrusion) of detoxification.