Fig. 7.

Claudin subtype-specific characteristics of formation of tight junction strands. Claudin-transfected HEK cells were analyzed by freeze-fracture electron microscopy. For Cld5_wt-expressing cells, discontinuous strands with intramembranous particles associated with the exoplasmic face (E-face) of the plasma membrane were detected (a). For Cld3_wt-expressing cells, continuous strands associated with the protoplasmic face (P-face) of the plasma membrane were detected (b). For cells that coexpress Cld5_wt-YFP and Cld3_wt, intramembranous particles were found on the E- as well as on the P-face (c). For cells transfected with Cld12 (d), Cld3_Y147A or non-transfected cells (latter not shown), and for non-transfected cells, no tight junction strands were observed