Article Addendum

The K+ battery-regulating Arabidopsis K+ channel AKT2 is under the control of multiple post-translational steps

Volume 6, Issue 4   April 2011
Pages 558 - 562
http://dx.doi.org/10.4161/psb.6.4.14908
Authors: Michael Sandmann, Kamil Skłodowski, Pawel Gajdanowicz, Erwan Michard, Marcio Rocha, Judith L. Gomez-Porras, Wendy González, Luiz Gustavo Guedes Corrêa, Santiago J. Ramírez-Aguilar, Tracey Ann Cuin, Joost T. van Dongen, Jean-Baptiste Thibaud and Ingo Dreyer

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Abstract:
Potassium (K+) is an important nutrient for plants. It serves as a cofactor of various enzymes and as the major inorganic solute maintaining plant cell turgor. In a recent study, an as yet unknown role of K+ in plant homeostasis was shown. It was demonstrated that K+ gradients in vascular tissues can serve as an energy source for phloem (re)loading processes and that the voltage-gated K+ channels of the AKT2-type play a unique role in this process. The AKT2 channel can be converted by phosphorylation of specific serine residues (S210 and S329) into a non-rectifying channel that allows a rapid efflux of K+ from the sieve element/companion cells (SE/CC) complex. The energy of this flux is used by other transporters for phloem (re)loading processes. Nonetheless, the results do indicate that post-translational modifications at S210 and S329 alone cannot explain AKT2 regulation. Here, we discuss the existence of multiple post-translational modification steps that work in concert to convert AKT2 from an inward-rectifying into a non-rectifying K+ channel.

Article Addendum to:
P Gajdanowicz, E Michard, M Sandmann, M Rocha, LG Corrêa, SJ Ramírez-Aguilar, JL Gomez-Porras, W González, JB Thibaud, Dongen JT van, I Dreyer. Potassium (K+) gradients serve as a mobile energy source in plant vascular tissues. Proc Natl Acad Sci U S A 2011; 108: 864-9
PMID: 21187374 DOI: 10.1073/pnas.1009777

Received: January 21, 2011; Accepted: January 23, 2011

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