Scrib PDZ domains are required for the junctional localization of Dlg and planar spindle alignment. (A) Mud (red) localizes at spindle poles and the cortex during mitosis, including the apical septate junctions as defined by Scrib localization (green). xy Images (upper panels) and xz images (lower panels). (B) Domain structure of wild-type Scrib and two mutant forms. The protein product of scrib⁴ retains only the LRR domains (ΔPDZs). scrib⁵ retains the LRR domains along with PDZ domains 1 and 2 (ΔPDZ 3–4). E-cad, E-cadherin. (C and D) Quantification of mitotic spindle alignment in scrib⁵ (C) and scrib⁴ (D) MARCM clones. The red and green lines show the median angular deviation for mutant clones and controls, respectively. n indicates the number of spindles observed. FRT82B clones (n = 33) for control. ****, P < 0.0001; n.s., not significant (P > 0.05) by Kolmogorov–Smirnov test. (E–H) E-cadherin and Dlg localization in scrib⁵ (E and G) and scrib⁴ (F and H) MARCM clones, respectively. MARCM clones were generated by using hsFLP UAS-mCD8-GFP; tub-Gal4 FRT82B tub-Gal80/TM6C with FRT82 recombined mutant lines. Upper panels are xy images; lower panels are cross sections (xz). Scale bars: 5 µm (A, C, and D) and 10 µm (E–H).