| GAP43 (growth associated protein 43) is a neuron specific, intrinsically disordered protein that concentrates in axonal growth cones and synaptic terminals and functions as a central modulator of neurite outgrowth, axon pathfinding, and synaptic plasticity during development and regeneration. It is targeted to the cytoplasmic face of the inner leaflet of the plasma membrane through dual palmitoylation and associates with phosphatidylinositol 4,5 bisphosphate and calmodulin, enabling it to translate presynaptic and growth cone calcium signals into cytoskeletal remodeling and membrane trafficking. A key regulatory site, Ser41, is phosphorylated by protein kinase C in a Ca2+ dependent manner, and this phosphorylation dynamically controls the affinity of GAP43 for calmodulin, thereby coordinating the release of actin associated regulatory complexes, actin polymerization at the leading edge, and microtubule advance into the growth cone, which collectively drive axon elongation and branching. In the developing and adult brain, GAP43 rich circuits are essential for formation of functional cortical connectivity, hippocampal plasticity, and activity dependent refinement of synaptic terminals, making GAP43 expression and phosphorylation status widely used readouts for regenerative competence and synaptic remodeling in experimental models. In schizophrenia and Alzheimer’s disease, altered GAP43 expression and mislocalization are observed in specific brain regions, where aberrant regulation of growth cone like dynamics and synaptic stability may contribute to disrupted connectivity and cognitive decline, so that GAP43 dependent signaling is ultimately dysregulated in neurodevelopmental and neurodegenerative contexts. |
Lane 1: Mouse brain
