The Na-K-ATPase 1 1 heterodimer as a cell adhesion molecule in epithelia

Vagin O, Dada LA, Tokhtaeva E, Sachs G. The Na-K-ATPase 1 1 heterodimer as a cell adhesion molecule in epithelia. Am J Physiol Cell Physiol 302: C1271–C1281, 2012. First published January 25, 2012; doi:10.1152/ajpcell.00456.2011.—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-ATPasedriven 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 1 subunit for the Na-K-ATPase transdimerization and intercellular adhesion. Furthermore, a possible role of N-glycans linked to the Na-K-ATPase 1 subunit in regulation of epithelial junctions by modulating 11 interactions is discussed.