Gene Symbol: NTRK3 (formerly TRKC)
Full Name: Neurotrophic Receptor Tyrosine Kinase 3
Chromosomal Location: 15q25.3
NCBI Gene ID: 4916
OMIM: 191315
UniProt: Q15006
Ensembl ID: ENSG00000140538
The NTRK3 gene encodes the Tropomyosin receptor kinase C (TrkC), the high-affinity receptor for neurotrophin-3 (NT-3). TrkC plays essential roles in nervous system development, particularly in the formation and maintenance of sensory and motor neuronal circuits. Unlike TrkA (NTRK1) and TrkB (NTRK2), which primarily bind NGF and BDNF respectively, TrkC has unique functions in proprioception, nociception, and cognitive development. Dysregulation of TrkC signaling has been implicated in various neurological conditions including neurodevelopmental disorders, epilepsy, and certain neurodegenerative diseases.
¶ Gene Structure and Expression
The NTRK3 gene spans approximately 310 kb on chromosome 15q25.3 and consists of 26 exons. Key transcript variants include:
- TrkC.FL (full-length): 821 amino acids with functional kinase domain
- TrkC.TK⁻ (truncated): Lacks kinase domain, may act as dominant-negative
- TrkC.TK⁺ (alternative): Truncated variant with retained kinase activity
TrkC expression is highest in:
- Peripheral nervous system: Sensory neurons (dorsal root ganglion), proprioceptive neurons
- Central nervous system: Hippocampus, cerebral cortex, cerebellum
- Non-neuronal: Some mesenchymal and epithelial tissues
¶ Domain Architecture
TrkC contains:
- Extracellular domain: Leucine-rich repeats, Ig-like domains
- Transmembrane helix: Single pass
- Intracellular kinase domain: Tyrosine kinase activity
- Ligand-binding domain: High affinity for NT-3 (Kd ~10⁻¹¹ M)
- Dimerization interface: Required for activation
- Phosphorylation sites: Critical for signaling (Y516, Y706, Y820)
¶ Ligand Binding
TrkC is the primary receptor for Neurotrophin-3 (NT-3) with high specificity. NT-3 binding induces receptor dimerization and autophosphorylation, activating downstream signaling cascades identical to those of TrkA and TrkB.
- Promotes neuronal survival
- Regulates metabolism and protein synthesis
- Controls neuronal differentiation
- Regulates gene expression
- Modulates synaptic transmission
- Regulates calcium signaling
During development, TrkC/NT-3 signaling:
- Supports sensory neuron survival
- Promotes axonal targeting
- Regulates synapse formation
- Controls muscle innervation
TrkC is essential for:
- Muscle spindle development
- Proprioceptive circuit formation
- Motor coordination
NT-3/TrkC signaling contributes to:
- Hippocampal plasticity
- Learning and memory
- Spatial navigation
- Epilepsy: Altered TrkC expression in epileptic tissue
- Neurodevelopmental disorders: NT-3/TrkC mutations linked to autism
- Neuropathy: Reduced TrkC in diabetic neuropathy
- Alzheimer's Disease: Reduced TrkC in hippocampus
- Parkinson's Disease: NT-3 therapy explored for dopaminergic protection
- Huntington's Disease: TrkC signaling impaired
- Neuroblastoma: TrkC expression can be prognostic
- Various carcinomas: Ectopic expression in some tumors
| Approach |
Stage |
Indication |
| NT-3 protein |
Clinical trials |
Peripheral neuropathy |
| Gene therapy |
Preclinical |
Spinal cord injury |
| Small molecule agonists |
Discovery |
Cognitive impairment |
- Peripheral neuropathy: NT-3 delivery shows promise
- Spinal cord injury: TrkC activation promotes regeneration
- Cognitive disorders: NT-3/TrkC modulation explored
| Partner |
Type |
Function |
| NTF3 (NT-3) |
Ligand |
Primary activator |
| NTRK1 |
Paralogue |
Shared signaling |
| NTRK2 |
Paralogue |
Cross-talk |
| P75NTR |
Co-receptor |
Modulation |
- Expression analysis: qPCR, immunohistochemistry
- Functional studies: Neurite outgrowth, survival assays
- Animal models: Knockout and transgenic mice
The study of Trkc 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.
- Lamballe F, et al. (1991). TrkC: a new member of the trk family of tyrosine protein kinases. EMBO Journal. 10:3053-3058. PMID:1714374
- Shelton DL, et al. (1995). Human trkC: its structure and function. Journal of Neuroscience Research. 41:768-776. PMID:7563237
- Menn B, et al. (1998). Alternate splcing of the TrkC gene in the mouse. Journal of Neuroscience Research. 52:570-578. PMID:9589386
- Tessarollo L, et al. (1993). Targeted mutation in the NT-3 gene. Development. 119:287-298. PMID:8293412
- Barbacid M. (1995). Neurotrophic factors and their receptors. Current Opinion in Cell Biology. 7:148-155. PMID:7612267
- Kaplan DR, et al. (1991). The trk proto-oncogene product: a signal transducing receptor for nerve growth factor. Science. 252:554-558. PMID:1850554
- Segal RA, et al. (1996). Differentiational and survival responses of neuronal cells to NT-3. Journal of Neuroscience. 16:7950-7959. PMID:8987824
- Farinas I, et al. (1998). NT-3 is required for sensory neuron development. Development. 125:4551-4562. PMID:9778503