FIG. 5.

Influence of TcdB on association of TJ proteins with “raft like” membrane microdomains: Control (medium only) (C) and TcdB-exposed epithelial monolayers (90 cm²/condition) were isolated at 4°C in the presence of 1% TX-100 and separated in a linear 5 to 30% (weight/weight) sucrose gradient, and 0.5-ml fractions were analyzed. The profiles of light scattering at an optical density of 600 nm (OD 600 nm) and membrane alkaline phosphatase activity of the gradient fractions are shown. TX-100-insoluble complexes in 22% ± 2% sucrose (1.08 g/cm³) from control monolayers of cells exhibit peak light scattering at 600 nm and have prominent alkaline phosphatase activity. Significant changes in these profiles were not observed following incubation with TcdB for 2 h. Representative data from three individual experiments are shown.