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 biochemical properties of the H+-ATPase phosphorylation. In vitro phosphorylation on threonine residue in the C-terminus of the H+-ATPase was detected in microsomal fraction from Vicia guard cells. Furthermore, phosphorylation was also detected in plasma membrane fraction from etiolated seedlings of Arabidopsis. These results suggested that a protein kinase localized in the plasma membrane was a common in plant cells. We will report analysis of in vitro phosphorylation in the purified complex of the H+-ATPase from plasma membrane of Arabidopsis.
