Mechanism for regulating cell surface distribution of Na+,K(+)-ATPase in polarized epithelial cells
R W Hammerton1, K A Krzeminski, R W Mays
1Department of Molecular and Cellular Physiology, Stanford University School of Medicine, CA 94305-5426.
Abstract:
Restriction of sodium, potassium adenosine triphosphatase (Na+,K(+)-ATPase) to either the apical or basal-lateral membrane domain of polarized epithelial cells is fundamental to vectorial ion and solute transport in many tissues and organs. A restricted membrane distribution of Na+,K(+)-ATPase in Madin-Darby canine kidney (MDCK) epithelial cells was found experimentally to be generated by preferential retention of active enzyme in the basal-lateral membrane domain and selective inactivation and loss from the apical membrane domain, rather than by vectorial targeting of newly synthesized protein from the Golgi complex to the basal-lateral membrane domain. These results show how different distributions of the same subunits of Na+,K(+)-ATPase may be generated in normal polarized epithelial and in disease states.
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