Accumulating evidence suggests that 14-3-3 proteins are involved in the regulation of plant plasma membrane H+-ATPase activity. However, it is not known whether the 14-3-3 protein interacts directly or indirectly with the H+-ATPase. In this study, detergent-solubilized plasma membrane H+-ATPase isolated from fusicoccin-treated maize shoots was copurified with the 14-3-3 protein (as determined by protein gel blotting), and the H+-ATPase was recovered in an activated state. In the absence of fusicoccin treatment, H+-ATPase and the 14-3-3 protein were well separated, and the H+-ATPase was recovered in a nonactivated form. Trypsin treatment removed the 10-kD C-terminal region from the H+-ATPase as well as the 14-3-3 protein. Using the yeast two-hybrid system, we could show a direct interaction between Arabidopsis 14-3-3 GF14-Φ and the last 98 C-terminal amino acids of the Arabidopsis AHA2 plasma membrane H+-ATPase. We propose that the 14-3-3 protein is a natural ligand of the plasma membrane H+-ATPase, regulating proton pumping by displacing the C-terminal autoinhibitory domain of the H+-ATPase.
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Jahn, T., Fuglsang, A. T., Olsson, A., Brüntrup, I. M., Collinge, D. B., Volkmann, D., … Larsson, C. (1997). The 14-3-3 protein interacts directly with the C-terminal region of the plant plasma membrane H+-ATPase. Plant Cell, 9(10), 1805–1814. https://doi.org/10.1105/tpc.9.10.1805