FIGURE 7.

The a-c and a-c/2-c fusion proteins are incorporated into the F₀ complex. The F₀ complex preparations from the membranes of OM202recA⁻ strains transformed with pHP7 (a-c fusion), pHP808 (a-c/2-c fusion), or pBWU13 (wild type) were separated by SDS-PAGE and silver-stained. Three samples of each preparation containing 0.2, 1.0, or 5.0 μg of protein as indicated by the triangles are shown. Positions of molecular mass markers and their masses in kDa are shown on the left. Similar to wild type subunits a and c (37), the fusion proteins display anomalous electrophoretic mobility that does not correspond to their actual molecular weights, a common property of many highly hydrophobic proteins. The calculated and apparent molecular masses for subunit a are 30 and 26 kDa, respectively, for the a-c fusion protein, 38 and 28 kDa, and for the a-c/2-c fusion, 42 and 33 kDa.