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Catalytic domain of the Protein Tyrosine Kinase, Tropomyosin Related Kinase A PTKs catalyze the transfer of the gamma-phosphoryl group from ATP to tyrosine (tyr) residues in protein substrates. TrkA 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 TrkA to its ligand, nerve growth factor (NGF), results in receptor oligomerization and activation of the catalytic domain. TrkA is expressed mainly in neural-crest-derived sensory and sympathetic neurons of the peripheral nervous system, and in basal forebrain cholinergic neurons of the central nervous system. It is critical for neuronal growth, differentiation and survival. Alternative TrkA splicing has been implicated as a pivotal regulator of neuroblastoma (NB) behavior. Normal TrkA expression is associated with better NB prognosis, while the hypoxia-regulated TrkAIII splice variant promotes NB pathogenesis and progression. Aberrant TrkA expression has also been demonstrated in non-neural tumors including prostate, breast, lung, and pancreatic cancers. The TrkA 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.",