Heterologous Expression and Functional Analysis of Higher Plant Transport Proteins in Xenopus Oocytes

Abstract

Many of the structural and biophysical mechanisms of transport and membrane signal transduction in higher plant cells have remained largely unknown until recently. Current research has led to the cloning of several cDNAs encoding plasma membrane transport proteins from higher plants, including ion pumps, proton-coupled carriers, and ion channels. Further studies have shown that several types of these plant membrane transporters can be functionally expressed in Xenopus oocytes. These studies allow structure-function studies of the gene products and in some cases have for the first time enabled voltage-clamp studies revealing the biophysical mechanism of transport of these various membrane proteins. This article focuses on methods for the use of Xenopus oocytes as a heterologous expression system for plant transporters. As other publications have described the use of Xenopus oocytes for heterologous expression of mammalian ion channels and receptors, the present article will concentrate mainly on special considerations applicable to the study of plant ion transporters.