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Catalytic domain of the Protein Tyrosine Kinase, Tropomyosin Related Kinase B PTKs catalyze the transfer of the gamma-phosphoryl group from ATP to tyrosine (tyr) residues in protein substrates. TrkB is a receptor PTK (RTK) containing an extracellular region with arrays of leucine-rich motifs flanked by two cysteine-rich clusters followed by two immunoglobulin-like domains, a transmembrane segment, and an intracellular catalytic domain. Binding of TrkB to its ligands, brain-derived neurotrophic factor (BDNF) or neurotrophin 4 (NT4), results in receptor oligomerization and activation of the catalytic domain. TrkB is broadly expressed in the nervous system and in some non-neural tissues. It plays important roles in cell proliferation, differentiation, and survival. BDNF/Trk signaling plays a key role in regulating activity-dependent synaptic plasticity. TrkB also contributes to protection against gp120-induced neuronal cell death. TrkB overexpression is associated with poor prognosis in neuroblastoma (NB) and other human cancers. It acts as a suppressor of anoikis (detachment-induced apoptosis) and contributes to tumor metastasis. The TrkB subfamily is part of a larger superfamily that includes the catalytic domains of other kinases such as protein serine/threonine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",