Figure 6.

Effect of Lufaxin on the activation of factor B and C3 in reconstituted systems. (A) Cleavage of C3 by a preformed C3b-Bb complex. The complex was formed by incubation of a mixture of purified C3b, factor B, and factor D in the presence of Mg²⁺. After addition of EDTA, the complex was incubated with C3 and analyzed by immunoblotting using anti-C3a. The left panel shows incubations with 0, 100, and 200 nM C3 in the absence of Lufaxin, while the right panel shows the same set of concentrations in the presence of 1 µM Lufaxin. (B) Activation of factor B by factor D in a reconstituted C3b-B complex. Mixtures of C3b, factor B, and factor D were incubated in the presence and absence of 1 µM Lufaxin. Cleavage of factor B was evaluated by Western blot using anti-factor B. Cleavage is indicated by the appearance of Ba and Bb. The left panel shows results of incubations for 0, 2, and 10 min in the absence of Lufaxin, and the right panel shows the same incubations in the presence of Lufaxin.