Cycling of protons and Na+ across bacterial membranes is connected wit
h such vital bacterial functions as are ATP synthesis, pH and Na+ home
ostasis, motility, and solute transport. The Na+/H+ antiporter is the
universal device that couples these H+ and Na+ movements across bacter
ial membranes. The review is concerned with the new aspects of molecul
ar biology and physiology, regulation of activity as well as expressio
n of Na+/H+ antiporters in E. coli, alkalophilis, halophilis, anaerobi
c bacteria, and archabacteria. The possible role of Na+/H+ antiporter
in bioenergetic processes in these microorganisms is also discussed.