Involved in neuronal migration during development of the cerebral neocortex. May function in a cell autonomous and a non-cell autonomous manner and play a role in appropriate adhesion between migrating neurons and radial glial fibers. May also regulate growth and differentiation of dendrites. Homodimer. Interacts with AP2M1; required for clathrin-mediated endocytosis (By similarity). Highly expressed during development in ventricular zone, intermediate zone, cortical plate, striatum, hippocampus, and brain stem. N-glycosylated. O-glycosylated. Shedding of the extracellular domain and intramembrane cleavage produce several proteolytic products. The intramembrane cleavage releases a soluble cytoplasmic polypeptide that translocates to the nucleolus (By similarity).