Abstract
* Guard cell movements are regulated by environmental cues including, for example, elevations in extracellular Ca(2+) concentration. Here, the subcellular localization and physiological function of the Ca(2+)-sensing receptor (CAS) protein was investigated. * CAS protein localization was ascertained by microscopic analyses of green fluorescent protein (GFP) fusion proteins and biochemical fractionation assays. Comparative guard cell movement investigations were performed in wild-type and cas loss-of-function mutant lines of Arabidopsis thaliana. Cytoplasmic Ca(2+) dynamics were addressed in plants expressing the yellow cameleon reporter protein YC3.6. * This study identified CAS as a chloroplast-localized protein that is crucial for proper stomatal regulation in response to elevations of external Ca(2+). CAS fulfils this role through modulation of the cytoplasmic Ca(2+) concentration. * This work reveals a novel role of the chloroplast in cellular Ca(2+) signal transduction.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Arabidopsis / metabolism*
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Arabidopsis / physiology
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Arabidopsis / ultrastructure
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Arabidopsis Proteins / analysis
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Arabidopsis Proteins / chemistry
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / physiology*
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Calcium / metabolism*
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Calcium-Binding Proteins / analysis
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Calcium-Binding Proteins / genetics
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Calcium-Binding Proteins / physiology*
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Cell Fractionation
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Conserved Sequence
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Cytoplasm / metabolism
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Green Fluorescent Proteins / analysis
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Nicotiana / genetics
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Nicotiana / ultrastructure
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Plant Stomata / metabolism*
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Plant Stomata / physiology
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Receptors, Calcium-Sensing / analysis
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Receptors, Calcium-Sensing / genetics
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Receptors, Calcium-Sensing / physiology*
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Recombinant Fusion Proteins / analysis
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Sequence Analysis, Protein
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Signal Transduction / genetics
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Thylakoids / chemistry
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Thylakoids / physiology*
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Thylakoids / ultrastructure
Substances
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Arabidopsis Proteins
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CAS protein, Arabidopsis
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Calcium-Binding Proteins
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Receptors, Calcium-Sensing
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Recombinant Fusion Proteins
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Green Fluorescent Proteins
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Calcium