All gels in this figure are anti-SufI immunoblots. (A) Effect of pH on binding and transport efficiency. Shown is the effect of pH on pre-SufI binding (top), and on transport in the presence of 4 mM ATP with an ATP regenerating system (middle) or 4 mM NADH (bottom). The data were quantified as in Fig. 1C: (blue) precursor bound to pTat IMVs, (red) lipid-bound precursor, (green) translocon-bound precursor, (black, solid) precursor transported with NADH, and (black, open circles) precursor transported with ATP (n = 3). (B) Effect of KCl concentration on binding and transport efficiency. Key as in A (n = 3). (C) Effect of KK substitution for the RR motif (pre-SufI-KK-CCC) on pre-SufI binding and transport efficiency (Tr) (n = 3). (D) Effect of urea concentration on binding and transport efficiency. Key as in A (n = 3).