Abstract
Vacuole is the most prominent organelle in plant cell. It occupies 80-90% of the cell volume. It has been clarified that the vacuole has various important functions in plants, such as filling of the cell, storage, cytoplasmic homeostasis or lysis. Furthermore, vesicle transport and prevacuolar compartments are also playing important roles for the vacuolar functions. In this study, we analyzed the proteome of purified tonoplast from Arabidopsis cultured cells by combining SDS-PAGE separation and LC-MS/MS analysis. We identified about 200 proteins including H+ pumps, transporters and unannotated transmembrane proteins in the tonoplast fractions. The vacuolar vesicle transport is mainly functioning to target proteins to the vacuole, but recent our data suggests that the vesicle transport may be working for the cytoplasmic homeostasis of small molecules, too. We discuss a relationship between salt tolerance or ion homeostasis and vacuolar network in plant cell.
