Abstract
Blue light induces stomatal opening through the activation of the plasma membrane H+-ATPase. Recent investigations have demonstrated that blue light activates the H+-ATPase via phosphorylation on threonine residue in the C-terminus with subsequent binding of 14-3-3 protein to the phosphorylated C-terminus in guard cells. However, protein kinase and protein phosphatase, which catalyze phosphorylation and dephosphorylation of the H+-ATPase, are still unknown. In this study, we analyzed the H+-ATPase complex by gel filtration and blue native-PAGE in Vicia guard cells. The H+-ATPase complex was detected 300-500 kDa. Illumination of blue light had no effect on size of the H+-ATPase complex in guard cells. Interestingly, treatment of guard cells with a fungal toxin fusicoccin, an activator of the H+-ATPase, increased size of the H+-ATPase complex to 750 kDa. We will report analyzes of in vitro phosphorylation and dephosphorylation of the H+-ATPase in the purified complex.
