Figure 7.
Photoinactivation of Syt I impairs endocytosis after normal vesicle fusion at the Drosophila neuromuscular junction. A, Schematic of experimental protocol and results. Nerve stimulation causes exocytosis, but no endocytosis, at the shibirets restrictive temperature in both conditions. Synaptic vesicle proteins and membrane are therefore trapped at the plasma membrane. When returned to the permissive temperature, control synapses endocytose synaptic vesicles, as indicated by synapto-pHluorin fluorescence decay (Control). At synapses in which Syt I has been photoinactivated (FlAsH), there is no synapto-pHluorin fluorescence decay, indicating that endocytosis is blocked. B, Images demonstrating synapto-pHluorin intensity changes at the neuromuscular junction after the shift from the restrictive to the permissive temperature. Time indicates minutes at the permissive temperature. Modified from Poskanzer et al. (2003).