Abstract
Plant plasma membrane H+-ATPase creates an electrochemical gradient of H+ across the plasma membrane. Recent studies demonstrated that the H+-ATPase is activated via phosphorylation on threonine in the C-terminus with subsequent binding of 14-3-3 protein to the phosphorylated C-terminus in plant cells. However, protein kinase and protein phosphatase, which catalyze phosphorylation and dephosphorylation of the H+-ATPase, are still unknown. In this study, we analyzed in vitro dephosphorylation of the H+-ATPase. Dephosphorylation of the H+-ATPase was detected in both microsomal fraction from Vicia guard cells and plasma membrane fraction from etiolated seedlings of Arabidopsis. Furthermore, the dephosphorylations were inhibited in the presence of EDTA, a chelating agent for divalent cations. These results suggest that a divalent cation-dependent protein phosphatase localized in the plasma membrane is involved in dephosphorylation of the H+-ATPase. We'll report analysis of in vitro dephosphorylation of the H+-ATPase in the purified complex.
