Function
This gene is a member of the semaphorin family and encodes a protein with an Ig-like C2-type (immunoglobulin-like) domain, a PSI domain and a Sema domain. This secreted protein can function as either a chemorepulsive agent, inhibiting axonal outgrowth, or as a chemoattractive agent, stimulating the growth of apical dendrites. In both cases, the protein is vital for normal neuronal pattern development.
Semaphorin-3A is a secreted protein, or chemorepulser, secreted by surrounding tissues to guide migrating cells and axons in the developing nervous system of an organism which is critical for the precise formation of neurons and vasculature. Semaphorins, which are short range inhibitory proteins that act as axonal growth cone guidance molecules, are synthesized by neurons during axon pathfinding. Repulsive guidance cue semaphorin-3A (Sema3A) is a gene of the semaphorin family and is expressed by motorneurons to control motor axonal pathfinding. Axon pathfinding is the process by which neurons follow very precise paths, sends out axons, and react to specific chemical environments to reach the correct endpoint. During nervous system development, guidance cues, such as Semaphorin-3A induce the collapse and paralysis of neuronal growth cones. This repulsive cue for developing axons are signaled through receptor complexes containing Neuropilin-1 (NRP1), which is a protein receptor in active neurons.
The first of the CRMP proteins, CRMP2, was identified as an intracellular messenger required for the growth cone-collapse induced by semaphorin 3A.
Read more about this topic: SEMA3A
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