Receptor tyrosine kinase involved in nervous system and probably heart development. Upon binding of its ligand NTF3/neurotrophin-3, NTRK3 autophosphorylates and activates different signaling pathways, including the phosphatidylinositol 3-kinase/AKT and the MAPK pathways, that control cell survival and differentiation. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Exists in a dynamic equilibrium between monomeric (low affinity) and dimeric (high affinity) structures (By similarity). Binds SH2B2. Interacts with SQSTM1 and KIDINS220. Interacts with PTPRS (By similarity). Interacts with MAPK8IP3/JIP3 (By similarity). Ligand-mediated auto-phosphorylation. Belongs to the protein kinase superfamily. Tyr protein kinase family. Insulin receptor subfamily.