Fig. 6.
Presynaptic MTG regulates the synaptic ECM carbohydrate matrix. A: WGA-binding carbohydrates at the NMJ are upregulated by targeted neuronal MTG overexpression. Third instar NMJs from elav-GAL4/+ control (con; left) and elav:MTG (right) probed with TRITC-WGA (red) and anti-HRP (blue). Short arrows point to saturated WGA puncta; long arrows point to diffuse WGA outlining NMJ. B: VVA-binding carbohydrates are upregulated by neuronal MTG overexpression. Similar preparations as for WGA, but stained with TRITC-VVA. C: Integrins regulate the synaptic selectivity of VVA-labeled ECM carbohydrates. VVA (red) and anti-HRP labeling (blue) in control (left) and mysts1/mysxg43 mutant NMJs (right), showing elevated nonsynaptic expression in the mutant muscle. All panels show muscle 4 NMJ; detergent-free conditions were used for all results shown. Scale bars = 5 μm.