Subcellular Localization of Signal Peptide Fusion Proteins Expressed in E. coli

For expression of some proteins in Escherichia coli , export to the periplasmic space is preferred over conventional expression in the cytosol. Export can be accomplished by fusing the coding sequence to DNA encoding a signal peptide (e.g., using pET-22b), which is cleaved by the bacterial signal peptidase as the protein is exported into the space between the inner and outer membranes of E. coli . This protocol uses osmotic shock to release polypeptides from the periplasm. Although not quantitative, it should provide preliminary information on the cellular location of signal peptide fusion proteins.