Novel type Arabidopsis thaliana H+-PPase is localized to the Golgi apparatus

Vacuolar H+-PPase, a membrane bound proton-translocating pyrophosphatase found in various species including plants, some protozoan and prokaryotes, has been demonstrated to be localized to the vacuolar membrane in plants. Using a GUS reporter system and a green fluorescent protein (GFP) fusion protein, we investigated the tissue distribution and the subcellular localization, respectively, of a novel type H+-PPase encoded by AVP2/AVPL1 identified in the Arabidopsis thaliana genome. We showed that AVP2/AVPL1 is highly expressed at the trichoma and the filament of stamen. Furthermore, the fluorescence of GFP-tagged AVP2/AVPL1 shelved small dotlike structures that were observed throughout the cytoplasm of various Arabidopsis cells under a fluorescent microscope. The distribution of this dot-like fluorescent pattern was apparently affected by a treatment with brefeldin A. Moreover, we demonstrated that most dot-like fluorescent structures colocalized with a Golgi resident protein. These findings suggest that this novel type H+-PPase resides on the Golgi apparatus rather than the vacuolar membrane. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.