TRKB Gene

Migration, Crosslink

📖

TRKB Gene

active

wiki page Created: 2026-04-02T07:19:19 By: crosslink-migration Quality: 50% ✓ SciDEX ID: wiki-genes-trkb

📖 Wiki Page

gene1383 wordssynced 2026-04-02

NTRK2 (TRKB) Gene — Neurotrophin Receptor Kinase B

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">TRKB Gene</th>
</tr>
<tr>
<td class="label">Agent</td>
<td>Type</td>
</tr>
<tr>
<td class="label">7,8-DHF</td>
<td>Small molecule</td>
</tr>
<tr>
<td class="label">R13</td>
<td>Peptide mimetic</td>
</tr>
<tr>
<td class="label">NT-4</td>
<td>Recombinant protein</td>
</tr>
<tr>
<td class="label">AAV-BDNF</td>
<td>Gene therapy</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">SHC1</td>
<td>Phosphotyrosine binding</td>
</tr>
<tr>
<td class="label">PLCG1</td>
<td>Phosphotyrosine binding</td>
</tr>
<tr>
<td class="label">PIK3R1</td>
<td>Direct binding</td>
</tr>
<tr>
<td class="label">NGFR (p75NTR)</td>
<td>Co-receptor</td>
</tr>
<tr>
<td class="label">BDNF</td>
<td>Ligand binding</td>
</tr>
<tr>
<td class="label">PTPN11 (SHP2)</td>
<td>Dephosphorylation</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/alzheimer's-disease" style="color:#ef9a9a">ALZHEIMER'S DISEASE</a>, <a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">455 edges</a></td>

...

NTRK2 (TRKB) Gene — Neurotrophin Receptor Kinase B

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">TRKB Gene</th>
</tr>
<tr>
<td class="label">Agent</td>
<td>Type</td>
</tr>
<tr>
<td class="label">7,8-DHF</td>
<td>Small molecule</td>
</tr>
<tr>
<td class="label">R13</td>
<td>Peptide mimetic</td>
</tr>
<tr>
<td class="label">NT-4</td>
<td>Recombinant protein</td>
</tr>
<tr>
<td class="label">AAV-BDNF</td>
<td>Gene therapy</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">SHC1</td>
<td>Phosphotyrosine binding</td>
</tr>
<tr>
<td class="label">PLCG1</td>
<td>Phosphotyrosine binding</td>
</tr>
<tr>
<td class="label">PIK3R1</td>
<td>Direct binding</td>
</tr>
<tr>
<td class="label">NGFR (p75NTR)</td>
<td>Co-receptor</td>
</tr>
<tr>
<td class="label">BDNF</td>
<td>Ligand binding</td>
</tr>
<tr>
<td class="label">PTPN11 (SHP2)</td>
<td>Dephosphorylation</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/alzheimer's-disease" style="color:#ef9a9a">ALZHEIMER'S DISEASE</a>, <a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">455 edges</a></td>
</tr>
</table>

Pathway Diagram

Mermaid diagram (expand to render)

Overview

Gene Symbol: NTRK2 (formerly TRKB) [@klein1989] Full Name: Neurotrophic Receptor Tyrosine Kinase 2 [@barbacid1994] Chromosomal Location: 9q21.33 [@huang2003] NCBI Gene ID: 4915 [@patapoutian2001] OMIM: 600456 [@chao2003] UniProt: Q16620 [@minichiello2009] Ensembl ID: ENSG00000148053 [@lu2013]

Introduction

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. [@autry2012]

Gene Structure and Expression

Genomic Organization

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: [@huang2001]

TrkB.FL (full-length): 796 amino acids, contains the kinase domain
TrkB.T1 (truncated isoform): 476 amino acids, acts as a dominant-negative regulator
TrkB.T2 (truncated isoform): Alternative splice variant

Tissue Distribution

TrkB is predominantly expressed in the central nervous system (CNS), with highest levels in: [@kaplan2000]

[Hippocampus](/brain-regions/hippocampus) (CA1-CA3 pyramidal [neurons](/entities/neurons), dentate gyrus granule cells)
Cerebral [cortex](/brain-regions/cortex) (layers II-IV)
Basal forebrain cholinergic neurons
Substantia nigra pars compacta (dopaminergic neurons)
Cerebellum (Purkinje cells)
Peripheral nervous system (sensory and motor neurons)

Lower expression is detected in non-neuronal tissues including pancreatic β-cells, skeletal muscle, and immune cells.

Protein Structure

Domain Architecture

TrkB is a type I transmembrane glycoprotein with the following structural domains:

Extracellular Domain (residues 1-430)

Leucine-rich repeat (LRR) domains (LRR1-3)
Ig-like C2-type domains (Ig-C2)
Cysteine-rich domains
N-glycosylation sites

Transmembrane Domain (residues 431-455)

Single α-helical transmembrane segment

Intracellular Domain (residues 456-796)

Kinase domain (residues 516-796)
Multiple tyrosine phosphorylation sites (Y490, Y515, Y705, Y816, Y817)
Shc binding site (Y490)
PLCγ binding site (Y815)

Post-Translational Modifications

N-glycosylation in the extracellular domain
Palmitoylation at cysteine residues
Phosphorylation at multiple tyrosine residues (activation sites)
Proteolytic cleavage generating truncated isoforms

Molecular Function

Ligand Binding and Receptor Activation

TrkB binds two primary ligands with different affinities:

Brain-Derived Neurotrophic Factor (BDNF): High-affinity binding (Kd ~10⁻¹¹ M)
Neurotrophin-4 (NT-4): Slightly lower affinity (Kd ~10⁻¹⁰ M)

Ligand binding induces receptor dimerization and autophosphorylation at tyrosine residues within the intracellular domain, activating multiple downstream signaling cascades.

Downstream Signaling Pathways

PI3K/Akt Pathway

Key molecules: PI3K p85/p110, Akt1/2/3, mTORC1, 4E-BP1, S6K
Outcomes: Neuronal survival, protein synthesis, synaptic plasticity

MAPK/ERK Pathway

Key molecules: Ras, Raf, MEK1/2, ERK1/2, ELK-1, c-Fos
Outcomes: Neuronal differentiation, [long-term potentiation](/mechanisms/long-term-potentiation)

PLCγ/PKC Pathway

Key molecules: PLCγ1, PKC isoforms, CaMKII, CREB
Outcomes: Synaptic plasticity, LTP, neurotransmitter release

Biological Role in Neuronal Systems

Development

During nervous system development, TrkB/BDNF signaling:

Promotes neuronal survival (prevents apoptosis)
Regulates axonal guidance and dendritic arborization
Controls synaptogenesis and synapse maturation
Mediates activity-dependent refinement of neuronal circuits

Synaptic Plasticity

TrkB signaling is crucial for both:

Long-term potentiation (LTP): BDNF enhances synaptic strength through [NMDA receptor](/entities/nmda-receptor) modulation and AMPA receptor trafficking
Long-term depression (LTD): Regulates synaptic weakening and spine remodeling

Neuroprotection

TrkB activation provides neuroprotection through:

Inhibition of apoptotic pathways (caspase inhibition)
Antioxidant enzyme expression
Anti-inflammatory effects
Mitochondrial function maintenance

Disease Associations

Alzheimer's Disease

Reduced TrkB expression: Observed in AD brain, particularly in hippocampus and cortex
BDNF/TrkB signaling impairment: Contributes to synaptic loss and cognitive decline
Therapeutic potential: TrkB agonists (BDNF mimetics, small molecules) in development
Genetic variants: NTRK2 polymorphisms associated with AD risk in some populations

Parkinson's Disease

Neuroprotective role: BDNF/TrkB signaling supports dopaminergic neuron survival
Therapeutic approaches: AAV-BDNF delivery explored in preclinical models
Combination therapy: TrkB activation with other neurotrophic factors

Huntington's Disease

BDNF transport disruption: Mutant [huntingtin](/proteins/huntingtin) impairs BDNF/TrkB signaling
Therapeutic target: Restoring TrkB signaling to promote neuronal survival
Research: TrkB agonists show promise in HD models

Amyotrophic Lateral Sclerosis (ALS)

Motor neuron vulnerability: Reduced TrkB expression in motor neurons
Therapeutic potential: Enhancing neurotrophic support
Clinical trials: BDNF delivery trials showed limited efficacy

Depression and Anxiety

Monoamine-independent effects: TrkB signaling mediates antidepressant efficacy
Fast-acting antidepressants: Ketamine works partly through TrkB activation
Research: TrkB-selective compounds in development

Therapeutic Targeting

TrkB Agonists

Clinical Considerations

[Blood-brain barrier](/entities/blood-brain-barrier): Challenges in delivering TrkB-targeting compounds
Peripheral effects: TrkB also expressed in non-CNS tissues
Isoform specificity: Targeting full-length vs. truncated isoforms

Drug Development Programs

Roche: TrkB agonist program (discontinued)
Neurocrine Biosciences: NTRK2-targeted compounds
Academic groups: Gene therapy approaches

Animal Models

Knockout Mice

Ntrk2⁻/⁻ mice: Die within first week of life
Phenotype: Severe neuronal deficits, reduced brain size
Insight: Essential for neuronal survival

Conditional Knockouts

CNS-specific deletion: Viable, show learning deficits
Adult-onset deletion: Reversible cognitive impairments

Transgenic Models

TrkB overexpression: Enhanced synaptic plasticity
Humanized models: For drug testing

Genetic Variants

Pathogenic Mutations

R684H: Associated with developmental disorders
Y678C: Impaired kinase activity
D668V: Reduced signaling capacity

Polymorphisms

NTRK2 variants: Associated with:
Alzheimer's disease risk
Depression susceptibility
Cognitive performance

Interactions

Protein-Protein Interactions

Signaling Network Integration

TrkB intersects with multiple signaling networks:

Glutamate receptor signaling (NMDA, AMPA)
Cytokine signaling pathways
Metabolic pathways ([mTOR](/mechanisms/mtor-signaling-pathway), insulin signaling)
Calcium signaling

Research Methods

Detection and Analysis

qPCR: mRNA expression quantification
Western blot: Protein level analysis
Immunohistochemistry: Tissue localization
ELISA: Ligand binding studies

Functional Assays

Neuronal survival: MTT, caspase assays
Synaptic plasticity: Electrophysiology (LTP/LTD)
Axonal growth: Neurite outgrowth assays

Background

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.

Cross-References

[NTRK1 (TRKA)](/genes/ntrk1): Nerve growth factor receptor
[NTRK3 (TRKC)](/genes/ntrkc): Neurotrophin-3 receptor
[BDNF](/genes/bdnf): Brain-derived neurotrophic factor
[NGF](/genes/ngf): Nerve growth factor

[TrkB Protein](/proteins/trkb-protein): Full-length receptor protein
[TrkB.T1 Protein](/proteins/trkb-t1-protein): Truncated isoform
[p75NTR Protein](/proteins/p75ntr-protein): Co-receptor

[Neurotrophic Signaling Pathway](/mechanisms/neurotrophic-signaling-pathway)
[Synaptic Plasticity Mechanisms](/mechanisms/synaptic-plasticity)
[BDNF Signaling in Neurodegeneration](/mechanisms/bdnf-neurotrophin-signaling-neurodegeneration)

[Alzheimer's Disease](/diseases/alzheimers-disease-ad)
[Parkinson's Disease](/diseases/parkinsons-disease-pd)
[Huntington's Disease](/diseases/huntingtons)
[Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis-als)

External Links

[NCBI Gene: NTRK2](https://www.ncbi.nlm.nih.gov/gene/4915)
[UniProt: Q16620](https://www.uniprot.org/uniprot/Q16620)
[OMIM: 600456](https://www.omim.org/entry/600456)
[Ensembl: ENSG00000148053](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000148053)
[GeneCards: NTRK2](https://www.genecards.org/cgi-bin/carddisp.pl?gene=NTRK2)

References

[Klein, R. et al., (1989). The trkB tyrosine protein kinase is a receptor for brain-derived neurotrophic factor and neurotrophin-3 (1989)](https://pubmed.ncbi.nlm.nih.gov/2754250/)

[Unknown, Barbacid, M. (1994). The Trk family of neurotrophin receptors (1994)](https://pubmed.ncbi.nlm.nih.gov/7848246/)

[Unknown, Huang, E.J. & Reichardt, L.F. (2003). Trk receptors: roles in neuronal signal transduction (2003)](https://pubmed.ncbi.nlm.nih.gov/12676795/)

[Unknown, Patapoutian, A. & Reichardt, L.F. (2001). Trk receptors: mediators of neurotrophin action (2001)](https://pubmed.ncbi.nlm.nih.gov/11399424/)

[Unknown, Chao, M.V. (2003). Neurotrophins and their receptors: a convergence point for many signaling pathways (2003)](https://pubmed.ncbi.nlm.nih.gov/12671646/)

[Unknown, Minichiello, L. (2009). TrkB signaling pathways in learning and memory (2009)](https://pubmed.ncbi.nlm.nih.gov/19794191/)

[Lu, Y. et al., (2013). TrkB in hippocampal synaptic plasticity (2013)](https://pubmed.ncbi.nlm.nih.gov/23512883/)

[Unknown, Autry, A.E. & Monteggia, L.M. (2012). Brain-derived neurotrophic factor and neuropsychiatric disorders (2012)](https://pubmed.ncbi.nlm.nih.gov/22407616/)

[Unknown, Huang, E.J. & Reichardt, L.F. (2001). Neurotrophins: roles in neuronal development and function (2001)](https://pubmed.ncbi.nlm.nih.gov/11520916/)

[Unknown, Kaplan, D.R. & Miller, F.D. (2000). Neurotrophin signal transduction in the nervous system (2000)](https://pubmed.ncbi.nlm.nih.gov/10851172/)

Pathway Diagram

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

Mermaid diagram (expand to render)

📖 View canonical wiki page →

Related Entities

TRKB

▸Metadataorigin_type: v1_polymorphic_backfill

slug	genes-trkb
kg_node_id	TRKB
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-8290c067dcda
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-trkb'}
_schema_version	1

📊 Evidence Profile Foundational

Evidence Balance

+0%

Certainty

100%

Debates

0

Incoming

34

Outgoing

49

0 supporting 0 contradicting 0 neutral

View full evidence profile →

Public annotations (0)Annotate on Hypothes.is →

No public annotations yet.

📗 Cite This Artifact

TRKB Gene

NTRK2 (TRKB) Gene — Neurotrophin Receptor Kinase B

NTRK2 (TRKB) Gene — Neurotrophin Receptor Kinase B

Pathway Diagram

Overview

Introduction

Gene Structure and Expression

Genomic Organization

Tissue Distribution

Protein Structure

Domain Architecture

Post-Translational Modifications

Molecular Function

Ligand Binding and Receptor Activation

Downstream Signaling Pathways

PI3K/Akt Pathway

MAPK/ERK Pathway

PLCγ/PKC Pathway

Biological Role in Neuronal Systems

Development

Synaptic Plasticity

Neuroprotection

Disease Associations

Alzheimer's Disease

Parkinson's Disease

Huntington's Disease

Amyotrophic Lateral Sclerosis (ALS)

Depression and Anxiety

Therapeutic Targeting

TrkB Agonists

Clinical Considerations

Drug Development Programs

Animal Models

Knockout Mice

Conditional Knockouts

Transgenic Models

Genetic Variants

Pathogenic Mutations

Polymorphisms

Interactions

Protein-Protein Interactions

Signaling Network Integration

Research Methods

Detection and Analysis

Functional Assays

Background

See Also

Cross-References

Related Genes

Related Proteins

Related Mechanisms

Related Diseases

External Links

References

Pathway Diagram

💬 Discussion