FIG. 7.

Ib-induced CF release from DOPC-cholesterol liposomes and oligomer formation of Ib. (A) CF-loaded DOPC-cholesterol (1:1) liposomes were incubated with various amounts of Ib at 4°C (○) and 37°C (•) for 3 h. CF release was determined as described in Materials and Methods. Data are given as means ± standard errors (n = 5). (B) DOPC-cholesterol (1:1) liposomes were incubated with ¹²⁵I-Ib at 4°C (lanes 1 to 3) and 37°C (lanes 4 to 6) for 3 h. The membrane-bound toxin was solubilized and subjected to SDS-PAGE, followed by autoradiography. The concentrations of ¹²⁵I-Ib were as follows: lanes 1 and 4, 5 μg/ml; lanes 2 and 5, 10 μg/ml; lanes 3 and 6, 20 μg/ml.