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 (By similarity). Interacts with PTPRS (PubMed:25385546). Interacts with MAPK8IP3/JIP3 (By similarity). Additional isoforms seem to exist. Widely expressed but mainly in nervous tissue. Isoform 2 is expressed at higher levels in adult brain than in fetal brain. Ligand-mediated auto-phosphorylation. Defects in NTRK3 are associated with susceptibility to congenital heart defects (CHD). A disease characterized by congenital developmental abnormalities involving structures of the heart. CHD are the most common major birth defects and the leading cause of death from congenital malformations. Belongs to the protein kinase superfamily. Tyr protein kinase family. Insulin receptor subfamily.