HUMAN NERVE GROWTH FACTOR RECEPTOR TRKA
[NTRK1_HUMAN] Defects in NTRK1 are a cause of congenital insensitivity to pain with anhidrosis (CIPA) [MIM:256800]. CIPA is characterized by a congenital insensitivity to pain, anhidrosis (absence of sweating), absence of reaction to noxious stimuli, self-mutilating behavior, and mental retardation. This rare autosomal recessive disorder is also known as congenital sensory neuropathy with anhidrosis or hereditary sensory and autonomic neuropathy type IV or familial dysautonomia type II.          Defects in NTRK1 are a cause of thyroid papillary carcinoma (TPC) [MIM:188550]. TPC is a common tumor of the thyroid that typically arises as an irregular, solid or cystic mass from otherwise normal thyroid tissue. Papillary carcinomas are malignant neoplasm characterized by the formation of numerous, irregular, finger-like projections of fibrous stroma that is covered with a surface layer of neoplastic epithelial cells. Note=Chromosomal aberrations involving NTRK1 are found in thyroid papillary carcinomas. Translocation t(1;3)(q21;q11) with TFG generates the TRKT3 (TRK-T3) transcript by fusing TFG to the 3'-end of NTRK1; a rearrangement with TPM3 generates the TRK transcript by fusing TPM3 to the 3'-end of NTRK1; an intrachromosomal rearrangement that links the protein kinase domain of NTRK1 to the 5'-end of the TPR gene forms the fusion protein TRK-T1. TRK-T1 is a 55 kDa protein reacting with antibodies against the C-terminus of the NTRK1 protein.
[NTRK1_HUMAN] Receptor tyrosine kinase involved in the development and the maturation of the central and peripheral nervous systems through regulation of proliferation, differentiation and survival of sympathetic and nervous neurons. High affinity receptor for NGF which is its primary ligand, it can also bind and be activated by NTF3/neurotrophin-3. However, NTF3 only supports axonal extension through NTRK1 but has no effect on neuron survival. Upon dimeric NGF ligand-binding, undergoes homodimerization, autophosphorylation and activation. Recruits, phosphorylates and/or activates several downstream effectors including SHC1, FRS2, SH2B1, SH2B2 and PLCG1 that regulate distinct overlapping signaling cascades driving cell survival and differentiation. Through SHC1 and FRS2 activates a GRB2-Ras-MAPK cascade that regulates cell differentiation and survival. Through PLCG1 controls NF-Kappa-B activation and the transcription of genes involved in cell survival. Through SHC1 and SH2B1 controls a Ras-PI3 kinase-AKT1 signaling cascade that is also regulating survival. In absence of ligand and activation, may promote cell death, making the survival of neurons dependent on trophic factors.      Isoform TrkA-III is resistant to NGF, constitutively activates AKT1 and NF-kappa-B and is unable to activate the Ras-MAPK signaling cascade. Antagonizes the anti-proliferative NGF-NTRK1 signaling that promotes neuronal precursors differentiation. Isoform TrkA-III promotes angiogenesis and has oncogenic activity when overexpressed.     
Publication Abstract from PubMed
Nerve growth factor (NGF) is involved in the development and maintenance of the nervous system and has been implicated as a possible therapeutic target molecule in a number of neurodegenerative diseases, especially Alzheimer's disease. NGF binds with high affinity to the extracellular region of a tyrosine kinase receptor, TrkA, which comprises three leucine-rich motifs (LRMs), flanked by two cysteine-rich clusters, followed by two immunoglobulin-like (Ig-like) domains. We have expressed the second Ig-like domain as a recombinant protein in E. coli and demonstrate that NGF binds to this domain with similar affinity to the native receptor. This domain (TrkAIg(2)) has the ability to sequester NGF in vitro, preventing NGF-induced neurite outgrowth, and in vivo, inhibiting NGF-induced plasma extravasation. We also present the three-dimensional structure of the TrkAIg(2) domain in a new crystal form, refined to 2.0 A resolution.
Identification and structure of the nerve growth factor binding site on TrkA.,Robertson AG, Banfield MJ, Allen SJ, Dando JA, Mason GG, Tyler SJ, Bennett GS, Brain SD, Clarke AR, Naylor RL, Wilcock GK, Brady RL, Dawbarn D Biochem Biophys Res Commun. 2001 Mar 23;282(1):131-41. PMID:11263982
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.