The energy-driven movement of intracellular membrane-bounded particles from one region of the cell to another is mediated by translocator molecules which transport the particles along microtubules. In axons, retrograde movement is mediated by a protein called "cytoplasmic dynein," while anterograde movement is mediated by a different protein called "kinesin." In this project, the subcellular distribution of kinesin and cytoplasmic dynein will be determined by immunolocalization at the light and electron microscopic levels. The differential association of these proteins with vesicles moving in the orthograde vs. retrograde directions in axons will be assessed. The components of the outer mitochondrial membrane will be analyzed to determine the characteristics of that organelle which allow it to move bidirectionally in axons. Finally, cDNA clones of the genes coding for the translocator proteins will be isolated. These experiments have as their focus increasing our understanding of the motor molecules involved in the important cell biological phenomenon of intracellular particle motility.