Fig. 2. ASIP/PAR-3 distributes at the cell-cell junctions of various rat epithelial cells in a manner different from that of ZO-1. The differential distributions of ASIP/PAR-3 and ZO-1 are compared in rat forestomach (A-C), small intestine (E-G), and renal cortex (I-K). The samples were double stained with affinity-purified anti-ASIP antibody (C2-3AP, green) and anti-ZO-1 (red). In merged views (C,G,K), the yellow and orange signals show the co-localizations of ASIP/PAR-3 and ZO-1. In stratified squamous epithelium, ASIP/PAR-3 localizes at cell-cell junctions from the basal layer to the granular layer, and some cytoplasmic punctate patterns are observed (A). The localization of ZO-1 in the same field as in A is shown in B. The signal intensity of ZO-1 in the cell-cell junctions was much higher in the spinous layer than in the basal layer. ZO-1 is also detected in blood vessels (B, arrowhead), whereas ASIP/PAR-3 is not. As shown in the merged view (C) and indicated schematically in D, the relative signal intensities of ASIP/PAR-3 and ZO-1 differ along with epithelial differentiation. (D) Phase contrast image. Asterisk, lumen; BL, basal layer; GL, granular layer; HL, horny layer; LP, lamina propria; SL, spinous layer. In small intestine, ASIP/PAR-3 is concentrated in the subapical domain of epithelial cell-cell junctions (E) in a manner different from that of ZO-1 (F). As indicated in (B), ZO-1 signals are also detected in blood vessels (F, arrowheads). Unfilled arrowheads in G indicate that the signal intensity of ASIP/PAR-3 (green) in crypts is relatively higher than that of ZO-1 (red), whereas ZO-1 signal intensities are relatively higher in villus (asterisk). (H) Phase contrast image of the same field as E. As shown in I-K, the signal intensity of ASIP/PAR-3 (green) in proximal renal tubules (pt) is the same as in distal tubules (dt); however, that of ZO-1 (red) is much higher in distal renal tubules (dt) than proximal tubules (pt). (L) Schematic structure of proximal and distal renal tubules in a nephron. The number of TJ strands in epithelial cells of the distal renal tubule is much higher than in the proximal tubule. Bars, 40 µm (A), 20 µm (E), 10 µm (I).