Plexin-A3 is a coreceptor for SEMA3A and SEMA3F. It is necessary for signaling by class 3 semaphorins and subsequent remodeling of the cytoskeleton. Plexin-A3 plays a role in axon guidance in the developing nervous system. It regulates the migration of sympathetic neurons, but not of neural crest precursors. Plexin-A3 is required for normal dendrite spine morphology in pyramidal neurons. It may play a role in regulating semaphorin-mediated programmed cell death in the developing nervous system. Class 3 semaphorins bind to a complex composed of a neuropilin and a plexin. The plexin modulates the affinity of the complex for specific semaphorins, and its cytoplasmic domain is required for the activation of down-stream signaling events in the cytoplasm [taken from the Universal Protein Resource (UniProt) www.uniprot.org/uniprot/P51805].