Tropomyosin receptor kinase B (TrkB), also known as tyrosine receptor kinase B, a receptor for brain-derived neurotrophic factor (BDNF), is a member of the neurotrophic tyrosine receptor kinase (NTRK) family. This kinase is a membrane-bound receptor exclusively expressed in neurons of the central nervous system. TrkB mediates the multiple effects of neurotrophic factors such as BDNF, neurotrophin-4 (NT-4), and neurotrophin-3 (NT-3), which includes neuronal differentiation and survival. It has two distinct binding regions for BDNF within the extracellular domain with high affinity. Upon neurotrophin binding, TrkB phosphorylates itself and the downstream molecular members of the related signal pathways.
TrkB has been shown to play an important role in tumorigenesis and metastasis, and mutations in this gene are associated with obesity and mood disorders. Accordingly, BDNF/TrkB signaling is thought to be a potential therapeutic target for schizophrenia.