Fig. 3. Analyses of the subcellular distribution of TJ proteins. Immunofluorescence studies of claudins-1, -2 and -3 (red) and occludin (green) in MDCK-C7 (A), and -C11 (B) cells were performed using the confocal microscope technique (see Materials and Methods). Colocalization (yellow) was detected for all claudins, except for claudin-2 in MDCK-C7. Z-scans (C,D) as shown on the right or above the top views were performed in 200 nm steps over a range of 10 µm. The Z-scans of claudin-1 in C7 (C) and C11 (D) revealed that a marked expression of claudin-1 is detectable in subjunctional membrane areas in C11 (circles).