Fig. 3. TJ membranes are modified by tMLCK expression. Detergent-insoluble low-density membranes were isolated from control monolayers without tMLCK induction (closed circles on graphs) or 8 hours after induction of tMLCK expression (open circles on graphs). Fractions were analyzed by SDS-PAGE immunoblot for occludin, claudin-1, and claudin-2. GM1 ganglioside was detected with peroxidase-conjugated cholera toxin B subunit. Densitometric analysis (right) shows that tMLCK expression causes occludin to shift to fractions of higher density, whereas claudin-1, claudin-2 and GM1 distributions were not significantly changed. Results are typical of six independent experiments.