The kinesins constitute a large family of microtubule-dependent motor proteins, which are responsible for the distribution of numerous organelles, vesicles and macromolecular complexes throughout the cell. Individual kinesin members play crucial roles in cell division, intracellular transport and membrane trafficking events including endocytosis and transcytosis. KIF1C is a member of the KIF1/Unc104 family of kinesin-like proteins, which are involved in the transport of mitochondria or synaptic vesicles in axons. The human KIF1A gene encodes a neuron-specific motor protein that delivers synaptic vesicle precursors to nerve terminals. KIF1A is a monomeric, globular molecule and has rapid anterograde motor activity (1.2 microns/s). KIF1A-mediated axonal transport plays a critical role in viability, maintenance and function of neurons, particularly mature neurons. KIF1A is associated with organelles that contain synaptic vesicle proteins such as synaptotagmin, synaptophysin and Rab 3A.