Submitted by Ethan R. Graf on Tuesday, 11/8/2011, at 6:10 PM

Synapses are complex molecular machines that transfer information from one cell to another via the highly regulated release of neurotransmitter from presynaptic axon terminals. Following release, neurotransmitter activates receptors on the membrane of the associated postsynaptic cell, completing the process of communication. The multifaceted nature of the synapse and its ability to change over time requires numerous developmental and modulatory mechanisms to control its formation and function.

To investigate questions of synapse development, we utilize molecular, genetic, biochemical, and imaging tools available in Drosophila to study the larval neuromuscular junction (NMJ) as a model synapse. We have previously identified the protein Rab3 as playing a novel role in the formation and distribution of the presynaptic release machine among the hundreds of potential vesicle release sites that comprise an NMJ. In the rab3 mutant, visualization of essential protein components of the release apparatus reveals that release machinery is concentrated at a small fraction of available release sites. This results in the formation of a small number of “super sites” where vesicle release is enhanced while leaving the majority of sites devoid of proteins required for efficient vesicle release.

The mechanism by which Rab3 performs this function is not understood.  Thus, current work in my laboratory revolves around an exploration of how Rab3 functions at the Drosophila NMJ.