Abstract : The activation of phospholipase C (PLC) is a conserved mechanism of signal transduction in eukaryotes. While the basic enzymology of this process is well described, the mechanism by which these reactions are regulated remains less clear. Importantly, the lipid intermediates involved in PLC signaling are distributed across more than one cellular compartment raising questions about how their metabolism is regulated both in space and time. I will describe our experiments with Drosophila photoreceptors that seek to address key questions in this area. The outcomes are key to neuronal performance during high rates of stimulation.