Figure 3.

DSyd-1 localizes to a subcompartment surrounding the AZ core. (A) Boutons of larval NMJ innervating muscle 6/7. Most DSyd-1 clusters are found associated with BRP^Nc82 signal, labeling AZs, as seen in high-magnification images (right). (B) There was no DSyd-1 staining at dsyd-1–deficient NMJs. (C) Single confocal slices of junctions expressing DLiprin-α^GFP, as described in Fouquet et al. (2009). STED images of α-GFP labelings show DLiprin-α^GFP as discrete spots arranged around the AZ core labeled by BRP^Nc82. (D) Single confocal slices of NMJs stained for endogenous DSyd-1 (STED) and BRP^Nc82 (confocal). Distinct separable DSyd-1 spots closely resembling DLiprin-α distribution are arranged around the AZ center. (E) Merged images of several aligned planar imaged AZs of moderate size associated with three DLiprin-α or DSyd-1 clusters. The image shows BRP^Nc82 in confocal resolution, α-GFP–labeled NMJs (for DLiprin-α^GFP), or DSyd-1–labeled NMJs imaged with STED. The arrangement of DSyd-1 clusters resembles that of the DLiprin-α clusters. d_a, distance between single clusters associated with the AZ; d_b, distance between AZ associated cluster and AZ center; d_c, diameter of clusters associated with AZs. (F) Single confocal slices of junctions expressing DLiprin-α^GFP. STED images of α-GFP show DLiprin-α^GFP as discrete dots arranged around the AZ core labeled by BRP^Nc82, ranging from one or two dots at small AZs to four or five dots at mature-sized AZs. (G) Triple labeling for DLiprin-α^YFP, DSyd-1, and BRP. Bars: (A and B) 2 µm; (A and B, insets) 500 nm; (C and D), 1 µm; (C and D, insets): 250 nm; (E) 250 nm; (F) 250 nm; (G) 500 nm.