Drosophila amphiphysin is a post-synaptic protein required for normal locomotion but not endocytosis

Clathrin-mediated endocytosis is required to recycle synaptic vesicles for fast and efficient neurotransmission. Amphiphysins are thought to be multip rotein adaptors that may contribute to this process by bringing together ma ny of the proteins required for endocytosis. Their in vivo function, howeve r, has yet to be determined. Here, we show that the Drosophila genome encod es a single amphiphysin gene that is broadly expressed during development. We also show that, unlike its vertebrate counterparts, Drosophila Amphiphys in is enriched postsynaptically at the larval neuromuscular junction. To de termine the role of Drosophila Amphiphysin, we also generated null mutants which are viable but give rise to larvae and adults with pronounced locomot ory defects. Surprisingly, the locomotory defects cannot be accounted for b y alterations in the morphology or physiology of the neuromuscular junction . Moreover, using stimulus protocols designed to test endocytosis under mod erate and extreme vesicle cycling, we could not detect any defect in the ne uromuscular junction of the amphiphysin mutant. Taken together, our finding s suggest that Amphiphysin is not required for viability, nor is it absolut ely required for clathrin-mediated endocytosis. However, Drosophila Amphiph ysin function is required in both larvae and adults for normal locomotion.