Robin Stevens, 2006-

B.S., 2005, Stanford University

Neurons communicate via calcium-dependent exocytosis of synaptic vesicles containing neurotransmitters.  This process is highly regulated and depends on the coordination of a wide array of proteins that execute the steps of targeting, docking, fusion and endocytotic recycling of synaptic vesicles.  The synaptic vesicle cycle has been studied extensively, and the function of many proteins associated with these vesicles has been established.  However, the functions of synaptophysin and synaptogyrin, two distantly related and abundant tetraspanning synaptic vesicle membrane proteins, are still relatively unknown.  These proteins have been implicated in several steps of the synaptic vesicle cycle including the formation of a fusion pore or ion channel, vesicle biogenesis through cholesterol interactions, and the regulation of endocytosis via interactions with dynamin.  We hope to further elucidate the role of these proteins by studying a synaptogyrin null mutant in Drosophila melanogaster.  The Drosophila genome encodes a single synaptogyrin homologue and lacks a synaptophysin homologue, simplifying genetic analysis.  Generation of transgenic animals with a synaptogyrin tagged with GFP demonstrate the protein is enriched on synaptic vesicles.  Animals lacking synaptogyrin are viable and fertile with no overt motor defects.  However, further analysis may reveal more subtle defects in synaptic morphology and neurotransmission.