Tropomyosin receptor kinase C (TrkC), also known as NT-3 growth factor receptor, neurotrophic tyrosine kinase receptor type 3, or TrkC tyrosine kinase is a protein that in humans is encoded by the NTRK3 gene. TrkC is the high affinity catalytic receptor for the neurotrophin NT-3 (neurotrophin-3). As such, TrkC mediates the multiple effects of this neurotrophic factor, which includes neuronal differentiation and survival. The TrkC receptor is part of the large family of receptor tyrosine kinases. A "tyrosine kinase" is an enzyme which is capable of adding a phosphate group to the certain tyrosines on target proteins, or "substrates". A receptor tyrosine kinase is a "tyrosine kinase" which is located at the cellular membrane, and is activated by binding of a ligand via its extracellular domain. Other example of tyrosine kinase receptors include the insulin receptor, the IGF-1 receptor, the MuSK protein receptor, the vascular endothelial growth factor (VEGF) receptor, etc. The "substrate" proteins which are phosphorylated by TrkC include PI3 kinase. Function TrkC is the high affinity catalytic receptor for the neurotrophin-3 (also known as NTF3 or NT-3). Similar to other NTRK receptors and receptor tyrosine kinases in general, ligand binding induces receptor dimerization followed by trans-autophosphorylation on conserved tyrosine in the intracellular (cytoplasmic) domain of the receptor. These conserved tyrosine serve as docking sites for adaptor proteins that trigger downstream signaling cascades. Signaling through PLCG1, PI3K and RAAS, downstream of activated NTRK3, regulates cell survival, proliferation and motility Moreover, TrkC has been identified as a novel synaptogenic adhesion molecule responsible for excitatory synapse development. The TrkC locus encodes at least eight isoforms including forms without the kinase domain or with kinase insertions adjacent to the major autophosphorylation site. These forms arise by alternative splicing events and are expressed in different tissues and cell types. NT-3 activation of catalytic TrkC isoform promotes both proliferation of neural crest cells and neuronal differentiation. On the other hand, the binding of NT-3 to the non-catalytic TrkC isoform induces neuronal differentiation, but nor neuronal proliferation Family members Tropomyosin receptor kinases, also known as neurotrophic tyrosine kinase receptors (Trk) play an essential role in the biology of neurons by mediating Neurotrophin-activated signaling. There are three transmembrane receptors TrkA, TrkB and TrkC (encoded by the genes NTRK1, NTRK2 and NTRK3 respectively) make up the Trk receptor family. This family of receptors are all activated by neurotrophins, including NGF (for Nerve Growth Factor), BDNF (for Brain