A Proteomics Approach Highlights a Myriad of Transporters in the Arabidopsis thaliana Vacuolar Membrane.

To better understand plant vacuolar functions and identify new transporters present on the tonoplast, a proteomic work was initiated on Arabidopsis thaliana. A procedure was developed to prepare highly purified vacuoles from protoplasts isolated from Arabidopsis cell cultures, and a proteomics approach was designed to identify the protein components present in both the membrane and soluble fractions of the vacuoles. This procedure allowed the identification of 650 proteins, 2/3 of which copurify with the hydrophobic membrane fraction and 1/3 with the soluble fraction. With regard to function, only 20% of the proteins identified were previously known to be associated with vacuolar activities.