Synaptic vesicle secretion is dependent on the assembly of fusogenic SNARE complexes between the synaptic vesicle SNARE protein synaptobrevin, and plasma membrane SNAREs syntaxin and SNAP-25, a process known as priming. Consequently proteins that regulate SNARE complex formation during vesicle priming can significantly impact synaptic strength. We have recently demonstrated that the syntaxin binding protein, tomosyn inhibits UNC-13-dependent priming in C. elegans, tomosyn mutants exhibiting increased release due to enhanced priming. Analysis of vertebrate tomosyn indicates that the interaction between tomosyn and syntaxin is regulated by protein kinase A (PKA), an enzyme implicated in learning and memory. We therefore, hypothesized that tomosyn may be an important effector in PKA-dependent synaptic plasticity. We chose Drosophila to test this hypothesis, as the role of the PKA pathway in fly associative learning has been well established. Since there are currently no Drosophila tomosyn mutants, we used RNA interference to reduce tomosyn levels to 30% of wild-type, based on quantitative RT-PCR and tomosyn immunostaining at the neuromuscular junction (NMJ). The synaptic phenotype of the Drosophila tomosyn knockdown will be described and our initial efforts to examine the potential role of tomosyn in olfactory learning in flies will be presented.