Abstract
Growth-associated protein, GAP-43, is a polypeptide that is induced in neurons when they grow axons. We show by means of subcellular fractionation and immunohistochemical localization that GAP-43 is a component of neuronal growth cones as well as growing neurites; it is similar to a major phosphoprotein, pp46, of a growth cone-enriched subcellular fraction. These conclusions are consistent with the possibility that the induction of GAP-43/pp46 is an important event in the establishment of a productive growth state in which a neuron is competent to extend an axon.