Transport may involve one or more of each type of solute. For example, the Na+/Ca2+ exchanger, found in the plasma membrane of many cells, moves three sodium ions in one direction, and one calcium ion in the other.
Antiporters, such as Na+/H+ antiporter protein, allows ions H+ and Na+ to travel across a membrane in order to change a concentration gradient.[2] When pH within a cell is higher or lower than the optimal range it can be detrimental, therefore, the Na+/H+ antiporter detects the pH level out of range and is activated to transport ions as a homeostatic mechanism to bring the pH level back to optimal range. [3]
There are differences among the types of Na+/H+ antiporter families present in eukaryotes and prokaryotes. Prokaryotic organisms contain antiporter families such as NhaA, NhaB, NhaC, NhaD, NhaP, along with NapA.[2] The most prominent functions, including pH regulation, are completed by Na+/H+ antiporter family NhaA in prokaryotes like Escherichia coli. [2]
Plants are sensitive to high amounts of salt, which can halt certain necessary functions of the eukaryotic organism, including photosynthesis.[2] For the organisms to maintain homeostasis and carry out crucial functions, Na+/H+ antiporters are used to rid the cytoplasm of excess sodium by pumping Na+ out of the cell. [2] These antiporters can also close their channel to stop sodium from entering the cell, along with allowing excess sodium within the cell to enter into a vacuole. [2]