Functional domains of neuromodulin (GAP-43).

Although neuromodulin (GAP-43, B50, F1, pp46, protein 4) was first identified over a decade ago, the physiological function(s) of the protein and the molecular mechanism(s) for its biological activities are still an area of active investigation. Neuromodulin has been implicated in several biological processes in neurons, including growth and regeneration, synaptic plasticity and neurotransmitter release. The molecular mechanisms underlying these implied physiological roles have not been elucidated, but there are several molecular properties of neuromodulin that may be important for its function in neurons. In this review, we will discuss research which has defined several of the functional domains of neuromodulin, including its phosphorylation sites, calmodulin binding domain, membrane binding domain and growth cone targeting domain. We will also suggest possible molecular functions of neuromodulin based on its biochemical properties.