Tissue-specific drivers were used to restore kis expression in specific tissues of kis mutants including presynaptic motor neurons (using the elav-Gal4 driver), postsynaptic muscle (using the 24B-Gal4 driver), or glial cells (using the repo-Gal4 driver). A) High resolution confocal micrographs of terminal presynaptic motor neuron boutons (HRP, magenta) after internalization of the lipophilic dye FM 1-43FX (green) after one min stimulation with 90 mM KCl in genotypes as listed. Scale bar = 5 μm. B) Quantification of FM 1-43FX fluorescence intensity indicates that when kis is restored in postsynaptic muscles of kis mutants, presynaptic endocytosis returns to control levels. C) Quantification of FM 1-43FX fluorescence intensity after tissue-specific knockdown of Kis. Knockdown of Kis in all tissues using the Actin5c-Gal4 driver or in postsynaptic muscles using the 24B-Gal4 driver resulted in impaired endocytosis. D) Histograms show quantification as determined by wrMTrck of larval crawling behavior on an agar arena for 30 s. Distance traveled, maximum velocity, average velocity, and crawling velocity normalized to body size (body lengths per second). Restoring kis expression in all tissues led to enhanced larval crawling.