Phloem: the integrative avenue for resource distribution, signaling, and defense van Bel , Aart J. E. (Justus-Liebig-University, Giessen(Allemagne). Department of Biology, Institute of General Botany); Helariutta , Ykä (University of Helsinki, Helsinki(Finlande). Plant Molecular Biology Lab, Institute of Biotechnology,); Thompson , Gary A. (Pennsylvania State University, University Park, Pennsylvania(Etats-Unis). Department of Plant Science, College of Agricultural Sciences) ...
http://www.frontiersin.org/plant_science,
2013
Publication
Cytokinins are perceived by three related histidine kinases (CRE1, AHK2, and AHK3) in Arabidopsis. According to the current model, cytokinins activate CRE1 to have the kinase activity, resulting in ...autophosphorylation at the conserved histidine residue. The phosphoryl group is transferred to a phosphotransfer mediator (AHP1, 2, 3, 4, or 5), and then to a response regulator. We report that CRE 1 possesses not only kinase activity but also phosphatase activity, and the kinase activity is activated and the phosphatase activity is repressed by cytokinins. We further demonstrate that there is a bidirectional phosphorelay network downstream of the 3 cytokinin receptors, and the phosphorylation level of the network system is regulated by the dual activities of the CRE1.
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