GlcAT-P^SK1/Df(3L)BSC817 mutant larvae display an extended VNC phenotype, but do not show impaired locomotion in crawling assays, as compared to controls; their muscles 6 and 7 at abdominal segment 3 show a partial loss of basement membrane that is particularly evident at the neuromuscular junction (assessed by Ndg and fluorescent Vkg protein levels), a duplicated and ruptured basal laminae at the muscles boundary (in ultrastructure analyses), and a less branched neuromuscular junction with boutons mis-localized to the muscles boundary (despite of similar bouton number), as compared to controls; at the presynaptic region, the synaptic vesicles (i.e. <80nm structures) are significantly smaller, and both the presynaptic endosome-like vesicles (i.e. >80nm structures) and vesicle structures within 250nm from a T-bar are significantly less abundant, but the total number of vesicles per bouton area and the number of T-bars are not significantly affected, as compared to controls; at the postsynaptic region, the postsynaptic density (PSD) is significantly shorter and deeper, but the number of PSDs per bouton, the subsynaptic reticulum (SSR) thickness per bouton area, and SSR density are not significantly affected, as compared to controls.