Figure 3.

The integration of a membrane protein into, and the translocation of a secretory protein across, the cytoplasmic membrane of E. coli have different molecular requirements. MtlA (A) and OmpA (C) were synthesized in vitro in the presence of the reagents indicated (INV, E. coli membrane vesicles; U-INV, urea-extracted INV; FtsY [20 ng/μl], Ffh [8 ng/μl], SecA [80 ng/μl], SecB [80 ng/μl] and F₁-ATPase [40 ng/μl] indicate the purified proteins and the final concentrations used). For further details see Figure 2 legend. (B) The integration of MtlA into U-INV was analyzed in the presence of increasing amounts of Ffh (P48) while keeping the FtsY concentration constant and vice versa. Integration was quantified as detailed in Figure 2.