Abstract
A hydrophilic protein, Arabidopsis thaliana PCaP2 is composed of 168 amino acids and has an N-myristoylation signal at N-terminus. We found that PCaP2 binds Ca and phosphatidylinositol phosphates (PIPs). In this study, we investigated intracellular localization and tissue specificity. When PCaP2::GFP protein was expressed in Arabidopsis cells, green fluorescence was clearly observed in the plasma membrane. But fluorescence of PCaP2G2A::GFP whose Gly-2 was replaced with Ala was observed in the cytosol. The results indicate that PCaP2 binds to the plasma membrane via myristoylation at Gly-2. Observation of PCaP2promoter::PCaP2:GFP plants confirmed the plasma membrane localization. Promoter-GUS analysis showed the expression in root epidermal cells, root hairs and pollen tubes. PCaP2 is likely to function through the interaction with Ca and PIPs on the plasma membrane of epidermal cells. Since PCaP2 was reported as a microtuble-associated protein (Wang et al. 2007), we will discuss about these facts.
