Abstract
Vacuoles have various functions in plant cells, such as storage, lysis or stress tolerance. A large number of proteins in the tonoplast support those functions of the vacuole, including pumps, carriers and ion channels. To date, the limited proteins involved in the transport processes of the tonoplast have been identified at the molecular level. In this study, we analyzed the proteome of the tonoplast from Arabidopsis thaliana cultured cells by combining the use of highly purified tonoplast, fractionation of peripheral and transmembrane proteins, SDS-PAGE separation and LC-MS/MS analysis. We identified about 90 and 100 proteins each in peripheral and transmembrane fractions, respectively; about 30 proteins were commonly detected in both fractions. The identified proteins contained both novel transporters that had been postulated by the physiology of vacuoles and unannotated transmembrane proteins besides the major tonoplast proteins like V-H+-ATPase and V-H+-PPase. This study was partly supported by CREST, NEDO/METI and KAKENHI/MEXT.
