Membrane Protein Preparation Using Aqueous Polymer Two-Phase Systems

Abstract

Membrane proteins serve many fundamental functions for cells such as cell-cell interactions, signal transduction, and molecular transport both within and between cells. Bioinformatic analysis has estimated that transmembrane domain containing proteins represent about 20–30% of all open reading frames in sequenced genomes (1). In addition, many proteins are anchored to the membranes via lipidic posttranslational modifications such as glycosylphos-phatidyl inositol anchors or via interaction with other membrane proteins. In total, embrane anchored proteins represent a considerable portion of all cellular proteins. They also represent 70% of all known drug targets, which prioritize them in biomedical research (2). Consequently, profiling membrane proteomes will aid in both understanding basic biological processes and discovering novel targets for therapeutic agents. Membrane proteomics, however, is rendered difficult on several levels.