The Candida albicans Na+/H+ antiporter exports potassium and rubidium.

The Candida albicans Cnh1p belongs to the family of Na+/H+ antiporters (TC 2.A.36) but it transports besides toxic sodium and lithium also rubidium and potassium. Upon heterologous expression in a Saccharomyces cerevisiae salt-sensitive strain, the Cnh1p is targeted to the plasma membrane and its transport activity results in increased tolerance of cells to external alkali metal cations. The cation efflux activity of Cnh1p in S. cerevisiae depends on the gradient of protons across the plasma membrane, and a Cnh1p-mediated K+ efflux is involved in a cell response to sudden rise of cytoplasmic pH. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.