Abstract
Transporter-mediated Ca(2+) efflux from the cytoplasm is an important component of plant signal transduction. To elucidate the diversity and role of Ca(2+)/H(+) in controlling plant cytosolic Ca(2+) concentrations, homologs of CAX (for calcium exchanger) genes were cloned from Zea mays and Arabidopsis thaliana cDNA libraries. The A. thaliana homolog of CAX (AtHCX1) is 77% identical to CAX1 while the Z. mays homolog of CAX (ZmHCX1) is 64% identical to CAX1 in amino acid sequence. AtHCX1 transcripts appeared to be expressed in all tissues, and levels of AtHCX1 RNA increased after Ca(2+) or Na(+) treatment. When expressed in yeast mutants defective in vacuolar Ca(2+) uptake, ZmHCX1 and AtHCX1 failed to suppress the Ca(2+) sensitivity of these strains. These results imply that CAX-like genes may have functions in plant ion homeostasis that differ from those of previously characterized CAX genes.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Antiporters / genetics*
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Antiporters / physiology
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Arabidopsis / genetics*
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Blotting, Northern
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Calcium-Binding Proteins / genetics*
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Calcium-Binding Proteins / physiology
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Cation Transport Proteins*
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Cloning, Molecular
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DNA, Complementary / chemistry
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DNA, Complementary / genetics
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Gene Expression Regulation, Plant
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Genes, Plant / genetics*
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Genetic Complementation Test
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Genetic Variation
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Molecular Sequence Data
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Mutation
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Phylogeny
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RNA, Plant / genetics
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RNA, Plant / metabolism
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / growth & development
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Sequence Analysis, DNA
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Sequence Homology, Amino Acid
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Tissue Distribution
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Zea mays / genetics*
Substances
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Antiporters
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Calcium-Binding Proteins
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Cation Transport Proteins
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DNA, Complementary
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RNA, Plant
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calcium-hydrogen antiporters
Associated data
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GENBANK/AF256228
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GENBANK/AF256229