1:7:7 stoichiometry of Baz, DE-cad, and Arm at SAJs. (A–D) Mapping protein distributions. (A, top) X-y planes are shown with single-cell sides boxed. (middle) Montages of single-cell sides shown from apical surface to 12 µm basal (0.3-µm z steps). SAJ is shown in a bracket. Dots indicate five SAJs and are shown at 3-µm intervals. (bottom) SAJ parameters are shown (50 sides each). (B) SAJ RFI profiles are shown of DE-cad∷GFP (n = 288), Arm∷GFP (n = 229), and Baz∷GFP (n = 188). (C) IM RFI profiles (n = 50 each) are shown. (D) Maps of SAJ and IM RFIs are shown over cell cortex. (E–G) Embryo protein counts are shown. (E) Purified GST-GFP is shown (12% SDS-PAGE; coomassie). (F) Example ELISA assay is shown with GST-GFP standard curve, and Baz∷GFP late cellularization embryos are shown. (G) Graph of the example standard curve is shown (done in duplicate), and the example Baz sample is indicated in red. (H) Levels of GFP-tagged proteins versus endogenous proteins in WT embryos (3–7-h embryo lysates; 6% SDS-PAGE). Blots were probed with DE-cad, Arm, Baz, and β-tubulin antibodies (non–GFP-tagged portion of DE-cad∷GFP detected; Oda and Tsukita, 1999). (I) Protein counts are shown. (J) Single-plane images are shown with the same coverslips and settings. Late cellularization is shown. RFIs were measured at the 10 brightest SAJs and equal IM areas. Normalized means ± SD are shown for five embryos each. WB, Western blot.