Cation Antiports of Animal Plasma Membranes

ABSTRACT Both organic and inorganic solutes can be transported across biological membranes against their electrochemical gradient, by coupling to the downhill movement of another species. In animal cells, the underlying mechanism most often involves symport (cotransport) or antiport (countertransport) with either sodium or hydrogen ions. The energy invested in the uphill translocation of solutes is ultimately provided by hydrolysis of ATP by Na+-or H+-transporting ATPases and is transiently stored as potential energy in the form of an electrochemical gradient of these ions.