Characterization of a cDNA encoding the 55 kDa B regulatory subunit of Arabidopsis protein phosphatase 2A |
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Authors: | Sabine J. Rundle Andrew J. Hartung John W. Corum III Michael O'Neill |
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Affiliation: | (1) Department of Biology, Western Carolina University, 28723 Cullowhee, NC, USA;(2) Present address: Department of Biochemistry and Cell Biology, State University of New York, 11794 Stony Brook, NY, USA |
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Abstract: | Type 2A serine/threonine protein phosphatases (PP2A) are key components in the regulation of signal transduction and control of cell metabolism. The activity of these protein phosphatases is modulated by regulatory subunits. While PP2A activity has been characterized in plants, little is known about its regulation. We used the polymerase chain reaction to amplify a segment of a cDNA encoding the B regulatory subunit of PP2A from Arabidopsis. The amplified DNA fragment of 372 nucleotides was used as a probe to screen an Arabidopsis cDNA library and a full-length clone (AtB) of 2.1 kbp was isolated. The predicted protein encoded by AtB is 43 to 46% identical and 53 to 56% similar to its yeast and mammalian counterparts, and contains three unique regions of amino acid insertions not present in the animal B regulatory subunit. Genomic Southern blots indicate the Arabidopsis genome contains at least two genes encoding the B regulatory subunit. In addition, other plant species also contain DNA sequences homologous to the B regulatory subunit, indicating that regulation of PP2A activity by the 55 kDa B regulatory subunit is probably ubiquitous in plants. Northern blots indicate the AtB mRNA accumulates in all Arabidopsis tissues examined, suggesting the protein product of the AtB gene performs a basic housekeeping function in plant cells. |
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Keywords: | Arabidopsis serine/threonine phosphatase PP2A B regulatory subunit |
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