Abstract
The NHA1 gene of Saccharomyces cerevisiae, transcribed into a 3.5 kb mRNA, encodes a protein mediating Na+ and K+ efflux through the plasma membrane that is required for alkali cation tolerance at acidic pH. Deletion of the gene in a wild-type strain resulted in higher sensitivity to both K+ and Na+ at acidic pH. Measurements of cation loss in strains carrying deleted or overexpressed alleles of NHA1 demonstrated its role in K+ and Na+ efflux. In addition, high K+ and Na+ efflux observed upon alkalinization of the cytoplasm implies a role of Nha1p in the regulation of intracellular pH. Moreover, the overexpression of ENA1 and NHA1 genes in an ena1-4 delta-nha1 delta strain showed that the Nha1 alkalication antiporter is responsible for growth on high concentrations of KCl and NaCl at acidic pH, and Ena alkali-cation ATPases are necessary at higher pH values. Both systems have a complementary action to maintain the intracellular steady-state concentration of K+ and Na+.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenosine Triphosphatases / genetics
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Adenosine Triphosphatases / metabolism
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Antiporters / genetics
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Antiporters / immunology
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Antiporters / physiology*
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Blotting, Northern
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Blotting, Western
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Cation Transport Proteins*
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Cloning, Molecular
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Drug Tolerance / genetics
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Fungal Proteins / genetics
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Fungal Proteins / immunology
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Fungal Proteins / physiology
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Gene Deletion
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Gene Expression / genetics
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Genetic Vectors
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Homeostasis
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Hydrogen-Ion Concentration
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Ion Transport
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Membrane Proteins / genetics
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Membrane Proteins / immunology
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Membrane Proteins / physiology*
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Potassium / metabolism*
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Potassium-Hydrogen Antiporters
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Promoter Regions, Genetic / genetics
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Saccharomyces cerevisiae / drug effects
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / growth & development
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins*
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Salts / pharmacology
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Sodium / metabolism*
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Sodium-Hydrogen Exchangers / genetics
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Sodium-Hydrogen Exchangers / immunology
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Sodium-Hydrogen Exchangers / physiology*
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Sodium-Potassium-Exchanging ATPase
Substances
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Antiporters
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Cation Transport Proteins
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ENA1 protein, S cerevisiae
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Fungal Proteins
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Membrane Proteins
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NHA1 protein, S cerevisiae
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Potassium-Hydrogen Antiporters
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Saccharomyces cerevisiae Proteins
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Salts
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Sodium-Hydrogen Exchangers
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Sodium
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Adenosine Triphosphatases
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Sodium-Potassium-Exchanging ATPase
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Potassium