FIG. 5.

Subcellular localization of overproduced membrane proteins. (A) The subcellular localization of overproduced membrane proteins was determined by fractionation of cells lacking the SURE plasmid (parental) or cells containing the SURE plasmid with (+) or without (-) subtilin-induced expression of membrane proteins. For each model protein the best-producing strain was used. As a control for correct fractionation, the presence of BdbD (membrane protein) and TrxA (cytosolic protein) was determined in the samples of the S PlsY-producing strain. (B) For low-abundance proteins, the fractionation was repeated without lysozyme treatment of the cells, to avoid the (low) background signal caused by cross-reactivity of the secondary antibody to lysozyme. Filled and open arrowheads mark bands of overproduced membrane proteins.