A cell-free translation and proteoliposome reconstitution system for functional analysis of plant solute transporters.

We describe here a novel proteoliposome reconstitution system for functional analysis of plant membrane transporters that is based on a modified wheat germ cell-free translation system. We established optimized conditions for the reconstitution system with Arabidopsis thaliana phosphoenolpyruvate/phosphate translocator 1 (AtPPT1) as a model transporter. A high activity of AtPPT1 was achieved by synthesis of the protein in the presence of both a detergent such as Brij35 and liposomes. We also determined the substrate specificities of three putative rice PPT homologs with this system. The cell-free proteoliposome reconstitution system provides a valuable tool for functional analysis of transporter proteins.