What is "neuropilin"

n. Any of a group of glycoproteins which act as transmembrane receptors in neurons

Neuropilin is a protein receptor active in neurons.

There are two forms of Neuropilins, NRP-1 and NRP-2. They are transmembrane glycoproteins, and predominantly co-receptors for another class of proteins known as semaphorins. Of the semaphorins, NRP-1 and NRP-2 are specifically receptors for class-3 semaphorins, which, among many things, are responsible for axon guidance during the development of the nervous system in vertebrates.

Neuropilins work as co-receptors as they have a very small cytoplasmic domain and thus rely upon other molecules (normally plexins) to transduce their signals across a cell membrane. Neuropilins generally work as dimers and different combinations have different affinities for molecules. For example, NRP-1 homodimers have high affinity for Sema3A, whilst NRP-2 homodimers have high affinity for Sema3F. Another ligand for neuropilins is VEGF, a growth factor involved in the regulation of angiogenesis.

The pleiotropic nature of the NRP receptors results in their involvement in multiple signalling pathways, such as axon guidance and angiogenesis, the immune response and remyelination.