Na+/H+ Exchangers of Mammalian Cells

Ejection of intracellular H+ in exchange for external Na+ is the most effective means of eliminating excess acid from actively metabolizing cells. Na+/H+ exchange is also crucial for the regulation of the cellular volume and for the reabsorption of NaCl across renal, intestinal, and other epithelia. This remarkable array of essential functions is carried out by a family of antiporters, known generically as Na+/H+ exchangers (NHEs).1 These are highly regulated (glyco)phosphoproteins present in virtually all mammalian tissues and species studied to date.