TrkC Protein

TrkC Protein — Tropomyosin Receptor Kinase C

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">TrkC Protein</th></tr>
<tr><td><strong>Protein Name</strong></td><td>Tropomyosin Receptor Kinase C</td></tr>
<tr><td><strong>Gene</strong></td><td>[NTRK3](/genes/ntrk3)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q16620](https://www.uniprot.org/uniprot/Q16620)</td></tr>
<tr><td><strong>PDB ID</strong></td><td>1HCF, 2ITM</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>145 kDa (full-length)</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Plasma membrane, endosomes</td></tr>
<tr><td><strong>Protein Family</strong></td><td>Trk receptor tyrosine kinase family</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
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Introduction

TrkC Protein — Tropomyosin Receptor Kinase C

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">TrkC Protein</th></tr>
<tr><td><strong>Protein Name</strong></td><td>Tropomyosin Receptor Kinase C</td></tr>
<tr><td><strong>Gene</strong></td><td>[NTRK3](/genes/ntrk3)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q16620](https://www.uniprot.org/uniprot/Q16620)</td></tr>
<tr><td><strong>PDB ID</strong></td><td>1HCF, 2ITM</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>145 kDa (full-length)</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Plasma membrane, endosomes</td></tr>
<tr><td><strong>Protein Family</strong></td><td>Trk receptor tyrosine kinase family</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Introduction

Tropomyosin receptor kinase C (TrkC), encoded by the NTRK3 gene, is a member of the Trk (tropomyosin receptor kinase) family of receptor tyrosine kinases[@barbacid1994]. TrkC serves as the high-affinity receptor for neurotrophin-3 (NT-3), a member of the neurotrophin family of growth factors that also includes nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-4/5 (NT-4)[@lessmann2003]. While TrkA and TrkB have been extensively studied in the context of neurodegeneration, TrkC has received less attention but represents an emerging area of research with significant therapeutic implications for neurodegenerative diseases.

Overview

TrkC is primarily expressed in proprioceptive [neurons](/entities/neurons), motor neurons, and certain populations of hippocampal and cortical neurons. Unlike TrkA (which preferentially binds NGF) and TrkB (which preferentially binds BDNF), TrkC has unique ligand specificity for NT-3[@snider1994]. This receptor plays critical roles in neuronal development, survival, and synaptic plasticity, and evidence suggests it may have neuroprotective properties in certain neurodegenerative conditions.

Background

The Trk family of receptor tyrosine kinases was discovered in the 1980s as oncogenic fusion proteins in certain cancers, leading to the identification of their normal roles in nervous system development. TrkC was identified as the third member of this family, with distinct expression patterns and ligand specificity compared to TrkA and TrkB[@patapoutian2001]. Research has shown that TrkC signaling follows both classical neurotrophin signaling pathways and unique mechanisms that are still being elucidated.

The NTRK3 gene, located on chromosome 15q25.3 in humans, encodes multiple isoforms of TrkC through alternative splicing. The full-length isoform (TrkC.FL) contains a functional tyrosine kinase domain, while truncated isoforms (TrkC.TK-) lack the kinase domain and may function as dominant-negative regulators or independent signaling molecules[@menn1998].

Structure

TrkC shares structural features with other Trk receptors:

Extracellular Domain

• Leucine-rich repeats (LRRs): Mediate initial ligand binding specificity
• Cysteine-rich domains: Stabilize ligand-receptor interactions
• Ig-like C2-type domains: Provide additional ligand interaction surfaces

Transmembrane Domain

• Single α-helical transmembrane helix connecting extracellular and intracellular domains

Intracellular Domain

• Tyrosine kinase domain: Catalytic activity for downstream signaling
• Multiple phosphorylation sites: Regulate signaling intensity and duration
• Docking sites: For adaptor proteins (Shc, PLC-γ)

Normal Function

TrkC is the primary receptor for neurotrophin-3 (NT-3)[@liu2012]:

Role in Disease

Alzheimer's Disease

• Reduced TrkC expression observed in [hippocampus](/brain-regions/hippocampus) of AD patients[@salehi1998]
• NT-3/TrkC signaling has neuroprotective effects against amyloid-β toxicity[@zhang2017]
• Potential therapeutic target for cognitive decline
• May modulate [tau](/proteins/tau) phosphorylation and aggregation

Parkinson's Disease

• TrkC expressed in dopaminergic neurons of substantia nigra
• NT-3 may protect against 6-OHDA and MPTP toxicity
• Therapeutic potential for motor symptoms

Amyotrophic Lateral Sclerosis (ALS)

• TrkC mutations linked to rare familial ALS cases
• Motor neuron survival supported by NT-3/TrkC signaling
• Gene therapy approaches using NT-3 under investigation

Neurodevelopmental Disorders

• Mutations in NTRK3 linked to neurodevelopmental syndromes
• Impaired NT-3/TrkC signaling affects neuronal development
• Associated with epilepsy and cognitive impairment

Therapeutic Implications

TrkC represents a promising therapeutic target:

See Also

• [NTRK3 Gene](/genes/ntrk3)
• [TrkA Protein](/proteins/trka-protein)
• [TrkB Protein](/proteins/trkb-protein)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Neurotrophic Factors](/mechanisms/neurotrophic-factors)

External Links

• [UniProt: trkc](https://www.uniprot.org/)
• [PubMed: trkc](https://pubmed.ncbi.nlm.nih.gov/?term=trkc+neurodegeneration)

References

Pathway Diagram

The following diagram shows the key molecular relationships involving TrkC Protein discovered through SciDEX knowledge graph analysis: