Neuronal migration of the central nervous system is a specialized form of cell motility that takes place in the laminar structure of the cortical regions of brain. Astrotactin is a neuronal cell surface protein expressed on postmitotic neuronal precursors in the cerebellum, hippocampus, cerebrum, and olfactory bulb. Astrotactin 2 is a paralog of Astrotactin. Astrotactin mediates neuron-astroglial interactions and is also implicated in synaptic development as well as many other neuronal activities. Astrotactin has three epidermal growth factor repeat domains and two fibronectin type III repeat domains. The human Astrotactin gene shows extensive homology to the mouse Astrotactin gene. Mutations in the Astrotactin gene are linked to neuronal migration defects in both species.