Mitochondria localization and transport are critical for neuronal function. Mitochondria produce ATP that supports many neuronal functions, and buffer calcium, an important regulator of many processes. My proposal focuses on a novel protein called Milton, which recent results in our lab suggest may play an important role in the trafficking of mitochondria. The striking phenotype of the milton mutant is that mitochondria are present in the cell body and absent in the nerve terminals of photoreceptors. We propose that Milton is essential for the trafficking of mitochondria in axons because in addition to the mutant phenotype, in HEK293T cells transfected with Milton, Milton co-localizes with mitochondria and kinesin, a molecular motor protein. In biochemical preparations of Drosophila heads Milton co-fractionates with mitochondria and co-immunoprecipitates with kinesin. My project will focus on understanding the biochemical mechanism of how Milton trafficks mitochondria. My specific aims are: to identify the functional domains of Milton that are essential for Milton-mediated transport of mitochondria; to identify proteins that interact with Milton; to show that Milton and its interacting proteins are essential for transport of mitochondria and further characterize their role in transport.