The polarized distribution of Na+,K+-ATPase: role of the interaction between {beta} subunits

• Published in: Molecular biology of the cell 2010-07, Vol.21 (13), p.2217-2225
• Main Authors: Padilla-Benavides, Teresita, Roldán, María L, Larre, Isabel, Flores-Benitez, David, Villegas-Sepúlveda, Nicolas, Contreras, Ruben G, Cereijido, Marcelino, Shoshani, Liora
• Format: Article
• Language: English
• Subjects: Animals; Cell Line; Cell Polarity; Cricetinae; Cricetulus; Dogs; Epithelial Cells - cytology; Epithelial Cells - metabolism; Fluorescence Resonance Energy Transfer; Models, Molecular; Protein Binding; Protein Conformation; Protein Isoforms - chemistry; Protein Isoforms - genetics; Protein Isoforms - metabolism; Protein Subunits - chemistry; Protein Subunits - genetics; Protein Subunits - metabolism; Rats; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Sodium-Potassium-Exchanging ATPase - chemistry; Sodium-Potassium-Exchanging ATPase - genetics; Sodium-Potassium-Exchanging ATPase - metabolism
• ISSN: 1939-4586
• DOI: 10.1091/mbc.E10-01-0081

The very existence of higher metazoans depends on the vectorial transport of substances across epithelia. A crucial element of this transport is the membrane enzyme Na(+),K(+)-ATPase. Not only is this enzyme distributed in a polarized manner in a restricted domain of the plasma membrane but also it creates the ionic gradients that drive the net movement of glucose, amino acids, and ions across the entire epithelium. In a previous work, we have shown that Na(+),K(+)-ATPase polarity depends on interactions between the beta subunits of Na(+),K(+)-ATPases located on neighboring cells and that these interactions anchor the entire enzyme at the borders of the intercellular space. In the present study, we used fluorescence resonance energy transfer and coprecipitation methods to demonstrate that these beta subunits have sufficient proximity and affinity to permit a direct interaction, without requiring any additional extracellular molecules to span the distance.