Department of Physiology, School of Medicine, University of California Los Angeles and Veterans Administration Greater Los Angeles Health Care System, Los Angeles, California, USA.
Am J Physiol Cell Physiol. 2012 May 1;302(9):C1271-81. doi: 10.1152/ajpcell.00456.2011. Epub 2012 Jan 25.
The ion gradients generated by the Na-K-ATPase play a critical role in epithelia by driving transepithelial transport of various solutes. The efficiency of this Na-K-ATPase-driven vectorial transport depends on the integrity of epithelial junctions that maintain polar distribution of membrane transporters, including the basolateral sodium pump, and restrict paracellular diffusion of solutes. The review summarizes the data showing that, in addition to pumping ions, the Na-K-ATPase located at the sites of cell-cell junction acts as a cell adhesion molecule by interacting with the Na-K-ATPase of the adjacent cell in the intercellular space accompanied by anchoring to the cytoskeleton in the cytoplasm. The review also discusses the experimental evidence on the importance of a specific amino acid region in the extracellular domain of the Na-K-ATPase β(1) subunit for the Na-K-ATPase trans-dimerization and intercellular adhesion. Furthermore, a possible role of N-glycans linked to the Na-K-ATPase β(1) subunit in regulation of epithelial junctions by modulating β(1)-β(1) interactions is discussed.
钠钾-ATP 酶产生的离子梯度通过驱动各种溶质的跨上皮转运，在上皮组织中起着至关重要的作用。这种钠钾-ATP 酶驱动的向量转运的效率取决于上皮连接的完整性，上皮连接维持着膜转运蛋白的极性分布，包括基底外侧的钠泵，并限制溶质的旁细胞扩散。这篇综述总结了表明，除了泵送离子之外，位于细胞-细胞连接处的钠钾-ATP 酶还通过与细胞间空间中相邻细胞的钠钾-ATP 酶相互作用，充当细胞黏附分子，同时锚定在细胞质中的细胞骨架上。这篇综述还讨论了关于钠钾-ATP 酶 β(1)亚基细胞外结构域中特定氨基酸区域对钠钾-ATP 酶转二聚体和细胞间黏附的重要性的实验证据。此外，还讨论了与钠钾-ATP 酶 β(1)亚基相连的 N-聚糖通过调节 β(1)-β(1)相互作用，可能在调节上皮连接中发挥作用。
