Ataxin-2 Protein (ATXN2)

Ataxin-2 Protein (ATXN2)

Overview

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">Ataxin-2 Protein (ATXN2)</th>
</tr>
<tr>
<td class="label">Domain</td>
<td>Location</td>
</tr>
<tr>
<td class="label">Lsm domain</td>
<td>N-terminus (1-89)</td>
</tr>
<tr>
<td class="label">PAM2 motif</td>
<td>90-150</td>
</tr>
<tr>
<td class="label">PolyQ tract</td>
<td>162-227</td>
</tr>
<tr>
<td class="label">PolyA-binding domain</td>
<td>700-850</td>
</tr>
<tr>
<td class="label">C-terminal</td>
<td>900-1318</td>
</tr>
<tr>
<td class="label">Feature</td>
<td>Details</td>
</tr>
<tr>
<td class="label">Repeat length</td>
<td>33-77 repeats (normal: 14-31)</td>
</tr>
<tr>
<td class="label">Onset age</td>
<td>30-50 years</td>
</tr>
<tr>
<td class="label">Phenotype</td>
<td>Cerebellar ataxia, slow saccades, peripheral neuropathy</td>
</tr>
<tr>
<td class="label">Neuropathology</td>
<td>Purkinje cell loss, pontine degeneration</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Stage</td>
</tr>
<tr>
<td class="label">ASO therapy</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">CRISPR</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">Stress granule modulators</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">Neuroprotective</td>
<td>Preclinical</td>
</tr>
</table>

Ataxin-2 Protein (ATXN2)

Overview

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">Ataxin-2 Protein (ATXN2)</th>
</tr>
<tr>
<td class="label">Domain</td>
<td>Location</td>
</tr>
<tr>
<td class="label">Lsm domain</td>
<td>N-terminus (1-89)</td>
</tr>
<tr>
<td class="label">PAM2 motif</td>
<td>90-150</td>
</tr>
<tr>
<td class="label">PolyQ tract</td>
<td>162-227</td>
</tr>
<tr>
<td class="label">PolyA-binding domain</td>
<td>700-850</td>
</tr>
<tr>
<td class="label">C-terminal</td>
<td>900-1318</td>
</tr>
<tr>
<td class="label">Feature</td>
<td>Details</td>
</tr>
<tr>
<td class="label">Repeat length</td>
<td>33-77 repeats (normal: 14-31)</td>
</tr>
<tr>
<td class="label">Onset age</td>
<td>30-50 years</td>
</tr>
<tr>
<td class="label">Phenotype</td>
<td>Cerebellar ataxia, slow saccades, peripheral neuropathy</td>
</tr>
<tr>
<td class="label">Neuropathology</td>
<td>Purkinje cell loss, pontine degeneration</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Stage</td>
</tr>
<tr>
<td class="label">ASO therapy</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">CRISPR</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">Stress granule modulators</td>
<td>Preclinical</td>
</tr>
<tr>
<td class="label">Neuroprotective</td>
<td>Preclinical</td>
</tr>
</table>

Ataxin-2 (encoded by the ATXN2 gene) is a 1,318 amino acid RNA-binding protein with multifaceted roles in RNA metabolism, stress granule dynamics, and translational control. It ispathologically expanded for Spinocerebellar Ataxia Type 2 (SCA2), and intermediate polyglutamine (polyQ) repeat expansions in ATXN2 are a recognized genetic risk factor for amyotrophic lateral sclerosis (ALS) and possibly Parkinson's disease (PD). [@lastorio2020][@gonzalez2019]

Protein Structure

Normal Function

Ataxin-2 is predominantly cytoplasmic and participates in:

Disease Associations

Spinocerebellar Ataxia Type 2 (SCA2)

SCA2 is caused by CAG repeat expansions in ATXN2 (>32 repeats), encoding an expanded polyQ tract:

Amyotrophic Lateral Sclerosis (ALS)

Intermediate ATXN2 repeat expansions (27-33 repeats) increase ALS risk:

• OR for ALS: 1.5-3.0 for intermediate repeats
• Pathogenesis: Altered stress granule dynamics, TDP-43 mislocalization
• Therapeutic targeting: ASO therapy targeting ATXN2 under development

Parkinson's Disease (PD)

Expanded ATXN2 repeats have been associated with PD risk:

• Association: Some PD cohorts show increased intermediate repeats
• Mechanism: May affect α-synuclein expression regulation
• Controversial: Not consistently replicated across populations

Pathogenic Mechanisms

Stress Granule Dysregulation

WT ataxin-2 localizes to stress granules during cellular stress:

Mutant ataxin-2 disrupts this cycle, leading to:

• Persistent stress granule formation
• Sequestration of translation components
• Impaired protein quality control

Transcriptional Dysregulation

Ataxin-2 interacts with:

• TDP-43 (TARDBP) — ALS-linked RNA binding protein
• FUS — ALS-linked nuclear protein
• SMN complex — splicing machinery

Therapeutic Approaches

Cross-Links

• [ATXN2 Gene](/genes/atxn2)
• [Spinocerebellar Ataxia Type 2](/diseases/sca2)
• [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Ataxin-1](/proteins/ataxin-1)
• [Stress Granules](/mechanisms/stress-granule-pathology)
• [TDP-43 Pathway](/mechanisms/tdp-43-proteinopathy)

References