Gene Symbol: NTRK2 (formerly TRKB) [1]
Full Name: Neurotrophic Receptor Tyrosine Kinase 2 [2]
Chromosomal Location: 9q21.33 [3]
NCBI Gene ID: 4915 [4]
OMIM: 600456 [5]
UniProt: Q16620 [6]
Ensembl ID: ENSG00000148053 [7]
The NTRK2 gene encodes the Tropomyosin receptor kinase B (TrkB), a member of the neurotrophic tyrosine receptor kinase (NTRK) family. TrkB is the high-affinity receptor for brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4), playing critical roles in neuronal survival, differentiation, synaptic plasticity, and cognitive function. TrkB signaling is essential for development and maintenance of the central and peripheral nervous systems, and its dysfunction has been implicated in various neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and Huntington's disease. [8]
The NTRK2 gene spans approximately 340 kb on chromosome 9q21.33 and consists of 24 exons. The gene encodes multiple transcript variants through alternative splicing, including: [9]
TrkB is predominantly expressed in the central nervous system (CNS), with highest levels in: [10]
Lower expression is detected in non-neuronal tissues including pancreatic β-cells, skeletal muscle, and immune cells.
TrkB is a type I transmembrane glycoprotein with the following structural domains:
Extracellular Domain (residues 1-430)
Transmembrane Domain (residues 431-455)
Intracellular Domain (residues 456-796)
TrkB binds two primary ligands with different affinities:
Ligand binding induces receptor dimerization and autophosphorylation at tyrosine residues within the intracellular domain, activating multiple downstream signaling cascades.
During nervous system development, TrkB/BDNF signaling:
TrkB signaling is crucial for both:
TrkB activation provides neuroprotection through:
| Agent | Type | Development Stage | Notes |
|---|---|---|---|
| 7,8-DHF | Small molecule | Preclinical | TrkB-selective agonist |
| R13 | Peptide mimetic | Preclinical | BDNF mimetic |
| NT-4 | Recombinant protein | Preclinical | Natural ligand |
| AAV-BDNF | Gene therapy | Preclinical | Viral vector delivery |
| Partner | Interaction Type | Functional Outcome |
|---|---|---|
| SHC1 | Phosphotyrosine binding | MAPK pathway activation |
| PLCG1 | Phosphotyrosine binding | PLCγ pathway activation |
| PIK3R1 | Direct binding | PI3K/Akt pathway activation |
| NGFR (p75NTR) | Co-receptor | Enhanced signaling |
| BDNF | Ligand binding | Receptor activation |
| PTPN11 (SHP2) | Dephosphorylation | Negative regulation |
TrkB intersects with multiple signaling networks:
The study of Trkb Gene has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
Klein, R. et al. (1989). The trkB tyrosine protein kinase is a receptor for brain-derived neurotrophic factor and neurotrophin-3. Cell. 1989. ↩︎
Barbacid, M. (1994). The Trk family of neurotrophin receptors. Journal of Neurobiology. 1994. ↩︎
Huang, E.J. & Reichardt, L.F. (2003). Trk receptors: roles in neuronal signal transduction. Annual Review of Biochemistry. 2003. ↩︎
Patapoutian, A. & Reichardt, L.F. (2001). Trk receptors: mediators of neurotrophin action. Current Opinion in Neurobiology. 2001. ↩︎
Chao, M.V. (2003). Neurotrophins and their receptors: a convergence point for many signaling pathways. Nature Reviews Neuroscience. 2003. ↩︎
Minichiello, L. (2009). TrkB signaling pathways in learning and memory. Learning & Memory. 2009. ↩︎
Lu, Y. et al. (2013). TrkB in hippocampal synaptic plasticity. Hippocampus. 2013. ↩︎
Autry, A.E. & Monteggia, L.M. (2012). Brain-derived neurotrophic factor and neuropsychiatric disorders. Pharmacological Reviews. 2012. ↩︎
Huang, E.J. & Reichardt, L.F. (2001). Neurotrophins: roles in neuronal development and function. Annual Review of Neuroscience. 2001. ↩︎
Kaplan, D.R. & Miller, F.D. (2000). Neurotrophin signal transduction in the nervous system. Current Opinion in Neurobiology. 2000. ↩︎