GENE-FUSION TECHNIQUES FOR DETERMINING MEMBRANE-PROTEIN TOPOLOGY

Gene-fusion systems for mapping membrane-protein topology depend on fu sing a reporter molecule which exhibits location-specific phenotypes t o progressively truncated versions of the membrane protein. The most e legant systems available are those developed for use in Escherichia co li where the reporters advertise whether they have been retained in th e cytoplasm by expression of simple phenotypes. The judicious applicat ion of such systems can reveal the organization of many proteins in th e bacterial cytoplasmic membrane, as well as providing insights into t he processes governing membrane assembly.