Synaptotagmin 7 splice variants differentially regulate synaptic vesicle recycling.

The speed of synaptic vesicle recycling determines the efficacy of neurotransmission during repetitive stimulation. Synaptotagmins are synaptic C(2)-domain proteins that are involved in exocytosis, but have also been linked to endocytosis. We now demonstrate that upon expression in transfected neurons, a short splice variant of synaptotagmin 7 that lacks C(2)-domains accelerates endocytic recycling of synaptic vesicles, whereas a longer splice variant that contains C(2)-domains decelerates recycling. These results suggest that alternative splicing of synaptotagmin 7 acts as a molecular switch, which targets vesicles to fast and slow recycling pathways.