FIG 6.

FH, C4BP, and vitronectin have distinct binding sites on LcpA. Competition inhibition assays were performed in which different amounts of C4BP (0 to 40 μg/ml) and a constant amount of FH (10 μg/ml) (A), different amounts of FH (0 to 40 μg/ml) and a constant amount of vitronectin (10 μg/ml) (B), or different amounts of C4BP (0 to 40 μg/ml) and a constant amount of vitronectin (10 μg/ml) (C) were added to immobilized LcpA (10 μg/ml). Molar ratios are indicated below the graphs. Bound molecules were detected using specific antibodies followed by peroxidase-conjugated secondary antibodies. Optical densities were determined at 492 nm. Data represent the means ± SD for 3 independent experiments, each performed in triplicate. Molar ratios found under physiological conditions are underlined.