Na⁺/H⁺ antiport in isolated plasma membrane vesicles from the halotolerant alga <i>Dunaliella salina</i>

Abstract

Plasma membrane vesicles isolated from the halotolerant alga Dunaliella salina catalyze Na + /H + antiport in a manner that is highly specific for Na + (apparent K m ≅ 16 mM). Li + and amiloride inhibit the process competitively with apparent K i values of 38 and 37 μM, respectively. It is suggested that Na + /H + antiport in this organism plays a major role in maintaining low intracellular Na + concentrations and may also function to drive Na + /HCO 3 − symport, an important step in photosynthetic carbon fixation.