Fig. 4. Subcellular localization of DLin-7 in wing imaginal discs and its recruitment by Sdt. (A-F) In wing imaginal discs DLin-7 is localized apical to Dlg, which is restricted to the septate junction in epithelia (A-C), and colocalizes with Sdt in the SAR (D-F). (G-I) ptc-Gal4-driven overexpression of Sdt increases apical levels of DLin-7. (G'-I') Note that both overexpressed Sdt and, as a consequence, DLin-7 are targeted to the SAR (white arrowheads mark the borders of the overexpression domain). (J) DLin-7 and Sdt-GUK interact in vitro. Sepharose beads carrying a GST-DLin-7 fusion protein or GST alone were incubated with biotinylated Sdt-GUK. Bound protein was eluted and analysed by SDS-PAGE. Binding was observed between GST-DLin-7 and Sdt-GUK (right lane), but not between GST and Sdt-GUK (middle lane). The left lane shows labelled Sdt-GUK protein equivalent to 10% of the material analysed in the experimental lanes. (K) Anti-mLin-7 antibody (Perego et al., 2002) immunoprecipitates Sdt from embryos overexpressing Sdt-MAGUK protein (GAL4^daG32/UAS-sdt^MAGUK, left lane), whereas a control IgG (anti-ß-Gal) does not (middle lane). The western blot was then probed with anti-Sdt antibody. The left lane shows the corresponding input control with approximately 50 µg of total protein from embryonic extracts.