Identification of regions required for apical membrane localization of human multidrug resistance protein 2
Identification of regions required for apical membrane localization of human multidrug resistance protein 2
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DOI：
10.1124/mol.108.045674
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发表时间：
2008-07-01
影响因子：
3.6
通讯作者：
Deeley, Roger G.
中科院分区：
文献类型：
--
作者：
Bandler, Paul E.;Westlake, Christopher J.;Deeley, Roger G.
多药耐药蛋白 MRP1 和 MRP2 转运多种内源性和外源性物质。然而，除了大脑的某些部分之外，MRP1 运输到极化细胞的基底外侧膜，而 MRP2 位于顶端，因此对于全身消除此类化合物特别重要。 MRP1 和 MRP2 的不同区域似乎将它们定位到各自的膜位置。除了 ATP 结合盒转运蛋白的两个“核心”跨膜结构域 (MSD) 特征外，MRP1 和 MRP2 还具有第三个 NH2 末端 MSD (MSD0)，这对于 MRP1 的基底外侧靶向或至少某些底物的转运不是必需的。在这里，我们证明了 MRP2 顶端靶向所需的所有元件都位于 MSD0 和相邻的细胞质环 (CL) 3 中。此外，我们表明 MRP2 的该区域可以将 MRP1 的核心靶向专门的顶端位置。在 MRP2 CL3 中，我们发现了一种富含赖氨酸的元素，这对于顶端靶向至关重要。当引入 MRP1 时，仅此元素就足以导致部分顶端定位。然而，仅针对顶膜似乎需要包含 MRP2 的 MSD0 和 CL3 的整个区域的完整性。由于 MRP1 的 CL3 对于几种化合物的结合、转运或两者都至关重要，因此我们还检查了包含全部或部分 MRP2 MSD0 和 CL3 的杂合体的功能。我们的结果表明 CL3 对于与测试的谷胱甘肽和葡萄糖醛酸结合物的相互作用很重要，但可能涉及不同的区域。
Multidrug resistance proteins MRP1 and MRP2 transport a wide range of endo-and xenobiotics. However, with the exception of certain parts of the brain, MRP1 traffics to basolateral membranes of polarized cells, whereas MRP2 is apical in location and thus it is particularly important for systemic elimination of such compounds. Different regions of MRP1 and MRP2 seem to target them to their respective membrane locations. In addition to two "core" membrane spanning domains (MSDs) characteristic of ATP-binding cassette transporters, MRP1 and MRP2 have a third NH2-terminal MSD (MSD0), which is not required for basolateral targeting of MRP1, or for transport of at least some substrates. Here, we demonstrate that all elements necessary for apical targeting of MRP2 reside in MSD0 and the adjacent cytoplasmic loop (CL) 3. Furthermore, we show that this region of MRP2 can target the core of MRP1 to an exclusively apical location. Within MRP2 CL3, we identified a lysine-rich element that is essential for apical targeting. When introduced into MRP1, this element alone is sufficient to result in partial apical localization. However, exclusive targeting to the apical membrane seems to require the integrity of the entire region encompassing MSD0 and CL3 of MRP2. Because CL3 of MRP1 is critical for binding, transport, or both of several compounds, we also examined the function of hybrids containing all, or portions of MRP2 MSD0 and CL3. Our results indicate that CL3 is important for interaction with both the glutathione and glucuronide conjugates tested, but that different regions may be involved.