The maintenance of ionic homeostasis in the cytoplasm is an essential and crucial physiological process for all living beings. At cellular level, Na+ concentrations are maintained by specialized Na+ transporting molecular machines, which operate in the cell or plasma membrane. In eukaryotes Na+ transporting P-type ATPase play an important role in Na+ homeostasis that is known as Na+/K+-ATPase in animal cells in which K+ acts as a counter ion for the exchange of sodium. Na+/K+-ATPase is not found in plants. In plants and fungi, proton gradients are maintained by plasma membrane H+-ATPase while in animal cells Na+ and K+ gradient is maintained by Na+/K+-ATPase. However, in case of algae, a few reports of Na+/K+-ATPase are available, that maintains optimum concentration gradients in the cytoplasm and is used by Na+/H+ antiporter to exchange of Na+ and H+ ions. The membrane potential derived as a result of ion gradients across the membrane is base for a variety of cellular processes. An active Na+ dependent cycle (P-type ATPase) is scarcely reported in algae as compared to marine bacteria/cyanobacteria and animals. The characterization of these transporter gene-encoding membrane transports in seaweed would contribute to the understanding of abiotic stress tolerance in these organisms. This review highlights the detailed account of algal along with animal type Na+-ATPase i.e. occurrence, properties, significance and their recent progress.
Keywords: Concentration gradient; Homeostasis; Membrane potential; Membrane transporter; Na+-ATPase; Na+/H+ antiporter.