Fig. 2.

The gap junction protein Cx43 is expressed on lipid rafts in enterocytes. A–C: IEC-6 cells were treated with Alexa555-cholera toxin as described in methods, then fixed, immunostained with anti-Cx43 antibodies, and evaluated by confocal microscopy. Shown are the distribution of lipid rafts (A), Cx43 (B), and the merged image (C), in which regions of colocalization of lipid areas and Cx43 are shown in yellow (arrows). D: subcellular fractionation of IEC-6 cells as obtained by sucrose density ultracentrifugation. Fractions were subjected to SDS-PAGE and immunoblotted for the indicated markers: caveolin-1 (Cav-1), lipid rafts; PMP-70, mitochondria; Na/K-ATPase, plasma membrane; TGN28, Golgi. Note that the lipid raft marker Cav-1 is most prominent on fractions 4–7. E: SDS-PAGE showing the expression of Cx43 on lipid raft enriched fractions from IEC-6 cells. Representative of at least 5 separate experiments.