Ren XL, Qi GN, Feng HQ, Zhao S, Zhao SS, Wang Y, Wu WH

Potassium transporters and channels play crucial roles in K(+) uptake and translocation in plant cells, which are essential for plant growth and development. AKT1 has been reported as an important K(+) channel in Arabidopsis roots involved in K(+) uptake. It is known that AKT1 is activated by a protein kinase ...

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CIPK23 interacting with two calcineurin B-like proteins CBL1/CBL9. The present study demonstrated that another CBL protein (CBL10) could also regulate AKT1 activity. The CBL10-overexpressing lines showed similarly sensitive phenotype as akt1 mutant under low K(+) conditions. In addition, the K(+) content of both CBL10-overexpressing lines and akt1 mutant plants were significantly reduced compared with wild-type plants. Moreover, CBL10 could directly interact with AKT1, which was verified in yeast two-hybrid, BiFC and Co-IP experiments. The results of electrophysiological analysis in both Xenopus oocytes and Arabidopsis root cell protoplasts demonstrated that CBL10 impairs AKT1-mediated inward K(+) currents. Furthermore, the results from yeast two-hybrid competition assay indicated that CBL10 may compete with CIPK23 for binding with AKT1 and negatively modulate AKT1 activity. The present study revealed a CIPK-independent regulatory mechanism of CBL proteins, which suggested that CBL10 directly regulates AKT1 activity and affects ion homeostasis in plant cells. © 2013 The Authors. The Plant Journal © 2013 Blackwell Publishing Ltd.

Date: Jan. 20, 2013

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