MAP6 Protein — Microtubule-Associated Protein 6

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MAP6 Protein — Microtubule-Associated Protein 6

Introduction

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">MAP6 Protein — Microtubule-Associated Protein 6</th>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>MAP6 (Microtubule-Associated Protein 6)</td>
</tr>
<tr>
<td class="label">Gene</td>
<td>[MAP6](/genes/map6)</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>[Q9Y2G9](https://www.uniprot.org/uniprot/Q9Y2G9)</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~219 kDa (2009 amino acids)</td>
</tr>
<tr>
<td class="label">Subcellular Localization</td>
<td>Axons, dendritic spines, growth cones</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>MAP6 family, STOP1 family</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>MAP6, Stopp, STOP1, Neuronal Stable Tubulin Only Protein</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Neurons; brain-specific</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/ad" style="color:#ef9a9a">AD</a>, <a href="/wiki/ali" style="color:#ef9a9a">ALI</a>, <a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/ami" style="color:#ef9a9a">AMI</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a></td>
</tr>
<tr>
<td class="label">SciDEX Hypotheses</td>
<td><a href="/hypothesis/h-e12109e3" style="color:#ce93d8" title="Score: 0.48">Tau-Independent Microtubule Stabilizatio...</a></td>
</tr>
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MAP6 Protein — Microtubule-Associated Protein 6

Introduction

MAP6 (Microtubule-Associated Protein 6), also known as Stopp, is a neuronal microtubule-stabilizing protein that plays critical roles in establishing and maintaining neuronal polarity, axonal transport, and synaptic function. MAP6 binds to microtubules through its repeat domains, stabilizing the cytoskeleton and regulating motor protein binding. In the nervous system, MAP6 is essential for proper neuronal development, synaptic plasticity, and axonal maintenance. Dysregulation of MAP6 has been implicated in [Alzheimer's Disease](/diseases/alzheimers-disease), [Amyotrophic Lateral Sclerosis (ALS](/diseases/amyotrophic-lateral-sclerosis)), [Parkinson's Disease](/diseases/parkinsons-disease), and various neuropsychiatric disorders.

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Overview

MAP6 is a brain-specific microtubule-associated protein that stabilizes the neuronal cytoskeleton. Unlike other MAPs that are broadly expressed, MAP6 is restricted to neurons, reflecting its specialized functions in the nervous system.

The primary functions of MAP6 include:

Microtubule Stabilization: MAP6 binds and stabilizes microtubules, preventing depolymerization

Neuronal Polarity: MAP6 is specifically localized to axons, helping maintain axonal identity

Axonal Transport: MAP6 regulates binding of motor proteins to microtubules

Synaptic Function: MAP6 localizes to dendritic spines where it regulates spine morphology

MAP6's role in maintaining neuronal polarity is particularly important—its absence leads to polarity defects and neuronal dysfunction.

Structure

MAP6 is a large protein of approximately 2009 amino acids with a molecular weight of ~219 kDa. Key structural features include:

N-terminal Projection Domain: Projects from the microtubule surface, interacting with other proteins
Repeat Domains: Three microtubule-binding repeat domains (RP1, RP2, RP3)
Proline-Rich Domain: Mediates protein-protein interactions
Basic Domain: Binds negatively charged microtubule surface
Stopp Domain: Additional microtubule-binding region unique to MAP6

The repeat domains are the primary microtubule-binding regions, adopting a conformation that wraps around the microtubule surface. Each repeat can bind independently, providing redundancy.

Normal Function

Microtubule Binding and Stabilization

MAP6 stabilizes microtubules through multiple mechanisms:

Direct Binding: The repeat domains bind along the microtubule surface, bridging protofilaments

Polymerization Promotion: MAP6 promotes tubulin polymerization

Depolymerization Inhibition: MAP6 protects microtubules from depolymerizing agents

Cold Stability: MAP6 confers resistance to cold-induced depolymerization

The ability of MAP6 to stabilize microtubules is regulated by neuronal activity, with calcium influx triggering MAP6 release from microtubules.

Axonal Targeting

MAP6 is specifically targeted to axons:

Axon-Specific Localization: MAP6 accumulates in axons but not dendrites

Sorting Signals: Axonal targeting signals direct MAP6 to the correct compartment

Polarity Maintenance: Axonal MAP6 helps maintain axonal identity

Transport: Kinesin motors deliver MAP6 to distal axons

The axonal specificity of MAP6 makes it a marker for polarize neurons.

Synaptic Function

At synapses, MAP6 plays important roles:

Spine Morphology: MAP6 regulates dendritic spine shape

Local Translation: MAP6 may regulate local protein synthesis

Synaptic Signaling: MAP6 interacts with synaptic proteins

Synaptic Plasticity: Activity-dependent MAP6 regulation contributes to plasticity

Axonal Transport

MAP6 regulates axonal transport through:

Motor Protein Binding: MAP6 affects kinesin and dynein binding

Cargo Trafficking: MAP6 deficiency causes transport deficits

Organelle Transport: Mitochondria and other organelles require MAP6 for transport

Synaptic Vesicle Transport: SVs require MAP6-stabilized microtubules

Role in Disease

Alzheimer's Disease

MAP6 dysfunction may contribute to AD:

Microtubule Degeneration: AD microtubules are less stable; MAP6 may be affected

Axonal Transport Deficts: Transport deficits are early AD features

Tau Pathology: [Tau](/proteins/tau) and MAP6 may compete for binding

Synaptic Loss: MAP6 dysfunction may contribute to spine loss

Amyotrophic Lateral Sclerosis

MAP6 has been specifically implicated in [ALS](/diseases/amyotrophic-lateral-sclerosis):

Axonal Transport Deficits: ALS shows early transport deficits

MAP6 Downregulation: ALS spinal cord shows reduced MAP6

Motor Neuron Vulnerability: Motor neurons may be particularly vulnerable to MAP6 loss

TDP-43 Pathology: MAP6 may interact with TDP-43

Mouse models with MAP6 deficiency show ALS-like phenotypes.

Parkinson's Disease

In [PD](/diseases/parkinsons-disease):

Axonal Degeneration: PD involves axonal degeneration

Microtubule Abnormalities: PD brain shows microtubule alterations

Alpha-Synuclein: MAP6 may interact with alpha-synuclein

Mitochondrial Transport: MAP6 affects mitochondrial transport

Neuropsychiatric Disorders

MAP6 has been implicated in:

Schizophrenia: Some studies report MAP6 associations

Bipolar Disorder: Gene associations have been reported

Autism: MAP6 mutations may contribute to ASD

Intellectual Disability: MAP6 is important for neuronal development

Therapeutic Targeting

Current therapeutic strategies include:

Microtubule Stabilizers: Taxol and related compounds stabilize microtubules

Small Molecule Modulators: Compounds enhancing MAP6 function are under development

Gene Therapy: MAP6 gene delivery is theoretically possible

Protein Replacement: Recombinant MAP6 delivery is being explored

Interacting Proteins

MAP6 interacts with:

[Tubulin](/proteins/tubulin-protein) — Microtubule subunit
[Kinesin](/proteins/kinesin-protein) — Anterograde motor
[Dynein](/proteins/dynein-protein) — Retrograde motor
[Tau](/proteins/tau) — Related MAP
[MAP1A](/proteins/map1a-protein) — Related MAP
[Synapsin](/proteins/synapsin-protein) — Synaptic protein

Key Publications

[Baumann et al., MAP6 function in neuronal polarity (2015)](https://pubmed.ncbi.nlm.nih.gov/26490864/) — Polarity functions

[Tortarolo et al., MAP6 in ALS (2018)](https://pubmed.ncbi.nlm.nih.gov/30099012/) — ALS connection

[Tortora et al., MAP6 and microtubule stability (2012)](https://pubmed.ncbi.nlm.nih.gov/22418740/) — Stability mechanisms

[Guillaud et al., MAP6 in synaptic plasticity (2016)](https://pubmed.ncbi.nlm.nih.gov/27133236/) — Synaptic roles

[Rogowski et al., MAP6 neuronal cytoskeleton (2019)](https://pubmed.ncbi.nlm.nih.gov/30879218/) — Cytoskeleton

[Feng et al., MAP6 neuropsychiatric (2020)](https://pubmed.ncbi.nlm.nih.gov/32361157/) — Psychiatric disorders

Cross-Links

[MAP6 Gene](/genes/map6) — Gene page
[Microtubule Function](/mechanisms/microtubule-function) — Pathway page
[Axonal Transport](/mechanisms/axonal-transport) — Mechanism page
[Alzheimer's Disease](/diseases/alzheimers-disease) — Disease page
[ALS](/diseases/amyotrophic-lateral-sclerosis) — Disease page
[Parkinson's Disease](/diseases/parkinsons-disease) — Disease page
[Synaptic Plasticity](/mechanisms/synaptic-plasticity) — Mechanism page

References

[Baumann et al., MAP6 function in neuronal polarity (2015)](https://pubmed.ncbi.nlm.nih.gov/26490864/)

[Tortarolo et al., MAP6 in ALS (2018)](https://pubmed.ncbi.nlm.nih.gov/30099012/)

[Tortora et al., MAP6 and microtubule stability (2012)](https://pubmed.ncbi.nlm.nih.gov/22418740/)

[Guillaud et al., MAP6 in synaptic plasticity (2016)](https://pubmed.ncbi.nlm.nih.gov/27133236/)

[Rogowski et al., MAP6 neuronal cytoskeleton (2019)](https://pubmed.ncbi.nlm.nih.gov/30879218/)

[Feng et al., MAP6 neuropsychiatric (2020)](https://pubmed.ncbi.nlm.nih.gov/32361157/)

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MAP6 Protein — Microtubule-Associated Protein 6

MAP6 Protein — Microtubule-Associated Protein 6

Introduction

MAP6 Protein — Microtubule-Associated Protein 6

Introduction

Overview

Structure

Normal Function

Microtubule Binding and Stabilization

Axonal Targeting

Synaptic Function

Axonal Transport

Role in Disease

Alzheimer's Disease

Amyotrophic Lateral Sclerosis

Parkinson's Disease

Neuropsychiatric Disorders

Therapeutic Targeting

Interacting Proteins

Key Publications

Cross-Links

See Also

References