Fig. 4: Interfering with the PDZ binding motif disrupts Nrx-1 subcellular distribution.
From: Versatile nanobody-based approach to image, track and reconstitute functional Neurexin-1 in vivo
a Diagram of Nrx-1-Gal4 organization. A MiMIC transposon, [MI10278], inserted right after exon 9 in the Nrx-1 gene, was converted with a Trojan T2A-Gal4 cassette inserted in the correct orientation and coding frame. The T2A-Gal4 in-frame insertion disrupts the expression of Nrx-1 and produces Gal4 instead. b, c Confocal micrographs of larval ventral cords (b) and synaptic terminals (c) of third instar larvae expressing UAS-CD4-tdTom and UAS-GFP.nls under Nrx-1-Gal4 control. Brp (white) marks the presynaptic active zones. The Nrx-1-Gal4 recapitulates the Nrx-1 endogenous expression pattern. d–g Deconvolved STED images of NMJ of third instar larvae expressing Nrx-1-AT (d) or Nrx-1-GFP (f) and stained for Nrx-1 (magenta) and either ALFA tag or GFP (green). Scatter plots of Nrx-1 and ALFA tag (e) or GFP (g) signals. Pearson’s coefficient in the co-localization volume shows a very high correlation for Nrx-1 and ALFA tags, but a low correlation for Nrx-1 and GFP signals. These experiments were repeated three times with similar results. h–j Summary bar graphs showing the mean amplitude of mEJPs (h), the mean amplitude of EJPs (i), and the QC (j) for the indicated genotypes; n = 10 for each genotype. k Quantification of bouton number for the indicated genotypes; n = 14 or more for each genotype. Scale bars: 100 µm (c), 10 µm (b”’, c’ and c”), and 2 µm (d and f). Data are represented as mean ± SEM (one-way ANOVA with Tukey’s multiple comparisons); ****p < 0.0001, ***p < 0.001, **p < 0.005, *p < 0.05, ns, p > 0.05. The boxes expand from the first to the third quartile, and the whiskers from minimum to maximum values; the center lines mark the mean values. Source data are provided as a Source Data file.
