Abstract
We report a structural and functional analysis of the PMR2 gene cluster in yeast. We found that several strains of Saccharomyces cerevisiae contain multiple PMR2 genes repeated in tandem, whereas most phylogenetically related yeasts appear to possess only a single PMR2 gene. This unusual tandem array of nearly identical genes encodes putative ion pumps involved in Na+ tolerance. Pmr2a and Pmr2b, the proteins encoded by the first two repeats, differ by only 13 amino acid exchanges. Both proteins share localization to the plasma membrane, but represent distinct isoforms of a putative Na+ pump. When expressed under identical conditions in vivo, Pmr2a and Pmr2b cause different tolerances to Na+ and Li+. Finally, we show that the Na+ tolerance mediated through these pumps is regulated by calmodulin via a calcineurin-independent mechanism which activates the Pmr2 ion pumps post-transcriptionally.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adenosine Triphosphatases / biosynthesis
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Adenosine Triphosphatases / genetics*
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Adenosine Triphosphatases / metabolism
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Calcineurin
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Calmodulin / physiology
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Calmodulin-Binding Proteins / physiology
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Cation Transport Proteins*
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Cell Fractionation
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Cell Membrane / enzymology
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Enzyme Induction
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Genes, Fungal / genetics
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Ion Transport / drug effects
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Isoenzymes / genetics*
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Lithium / pharmacology
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Multigene Family / genetics
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Mutation
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Phosphoprotein Phosphatases / physiology
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Promoter Regions, Genetic / genetics
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RNA, Fungal / biosynthesis
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RNA, Messenger / biosynthesis
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Recombinant Fusion Proteins / genetics
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Restriction Mapping
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Saccharomyces cerevisiae / drug effects
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae / genetics*
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Saccharomyces cerevisiae Proteins*
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Sodium / pharmacology
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Sodium-Potassium-Exchanging ATPase / biosynthesis
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Sodium-Potassium-Exchanging ATPase / genetics*
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Sodium-Potassium-Exchanging ATPase / metabolism
Substances
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Calmodulin
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Calmodulin-Binding Proteins
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Cation Transport Proteins
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ENA1 protein, S cerevisiae
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Isoenzymes
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RNA, Fungal
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RNA, Messenger
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Recombinant Fusion Proteins
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Saccharomyces cerevisiae Proteins
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Lithium
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Sodium
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Calcineurin
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Phosphoprotein Phosphatases
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Adenosine Triphosphatases
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Sodium-Potassium-Exchanging ATPase