MDA5 Protein
<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">MDA5 Protein</th>
</tr>
<tr> [@rice2014]
<td class="label">Gene</td>
<td><a href="/genes/ifih1">IFIH1</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/Q9QZF5" target="_blank">Q9QZF5</a></td>
</tr>
<tr>
<td class="label">PDB</td>
<td>3GA6, 4GL2, 5W5V</td>
</tr>
<tr>
<td class="label">Mol. Weight</td>
<td>116 kDa</td>
</tr>
<tr>
<td class="label">Localization</td>
<td>Cytoplasm</td>
</tr>
<tr>
<td class="label">Family</td>
<td>DEAD-box helicase family</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td><a href="/diseases/alzheimers">Alzheimer's Disease</a>, <a href="/diseases/parkinsons-disease">Parkinson's Disease</a>, <a href="/diseases/aicardi-goutieres">Aicardi-Goutières Syndrome</a></td>
</tr>
</table>
MDA5 Protein (IFIH1)
Introduction
Mda5 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Overview
...MDA5 Protein
<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">MDA5 Protein</th>
</tr>
<tr> [@rice2014]
<td class="label">Gene</td>
<td><a href="/genes/ifih1">IFIH1</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/Q9QZF5" target="_blank">Q9QZF5</a></td>
</tr>
<tr>
<td class="label">PDB</td>
<td>3GA6, 4GL2, 5W5V</td>
</tr>
<tr>
<td class="label">Mol. Weight</td>
<td>116 kDa</td>
</tr>
<tr>
<td class="label">Localization</td>
<td>Cytoplasm</td>
</tr>
<tr>
<td class="label">Family</td>
<td>DEAD-box helicase family</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td><a href="/diseases/alzheimers">Alzheimer's Disease</a>, <a href="/diseases/parkinsons-disease">Parkinson's Disease</a>, <a href="/diseases/aicardi-goutieres">Aicardi-Goutières Syndrome</a></td>
</tr>
</table>
MDA5 Protein (IFIH1)
Introduction
Mda5 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Overview
MDA5 (Melanoma Differentiation-Associated Protein 5), encoded by [IFIH1](/genes/ifih1), is a cytoplasmic pattern recognition receptor that detects viral RNA. It belongs to the DEAD-box helicase family and has a molecular weight of approximately 116 kDa^[@andrejeva2004]. This protein is localized to Cytoplasm and plays a significant role in the pathogenesis of [Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease), [Aicardi-Goutières Syndrome](/diseases/aicardi-goutieres).
Structure
The MDA5 protein has been characterized structurally through X-ray crystallography. Available PDB structures include: 3GA6, 4GL2, 5W5V^[@mott2016].
The protein's three-dimensional structure can also be explored via the [AlphaFold Protein Structure Database](https://alphafold.ebi.ac.uk/entry/Q9QZF5).
Normal Function
Under physiological conditions, MDA5 performs essential functions in antiviral immunity. It is primarily found in Cytoplasm and contributes to detecting viral RNA and initiating antiviral immune responses.
Viral RNA Sensing
MDA5 is a cytoplasmic RNA helicase that detects long double-stranded RNA:
- PAMP recognition — Binds long dsRNA (>1 kb in length)
- Viral specificity — Primarily detects picornaviruses, rotaviruses, noroviruses
- Signal transduction — Activates MAVS (mitochondrial antiviral signaling protein)
- Type I IFN induction — Triggers production of interferon-alpha/beta
Structure-Function
MDA5 contains multiple functional domains:
- C-terminal domain (CTD) — RNA binding
- Helicase domain — ATP-dependent RNA unwinding
- N-terminal CARD domains — Signal transduction via MAVS
MDA5 vs RIG-I
| Feature | MDA5 | RIG-I |
|---------|------|-------|
| Ligand | Long dsRNA (>1kb) | 5'PPP dsRNA, short dsRNA |
| Viruses | Picornaviruses | Influenza, HCV, VSV |
| Activation | Oligomerization | Conformational change |
Role in Disease
MDA5 is implicated in the following conditions:
- [Alzheimer's Disease](/diseases/alzheimers-disease) — [Aβ](/proteins/amyloid-beta) can activate MDA5 pathway; contributes to interferon response and neuroinflammation
- [Parkinson's Disease](/diseases/parkinsons-disease) — [α-synuclein](/proteins/alpha-synuclein) can trigger MDA5 activation; contributes to inflammatory response in [microglia](/entities/microglia)
- [Aicardi-Goutières Syndrome](/diseases/aicardi-goutieres) — Gain-of-function mutations cause constitutive interferon activation; early-onset encephalopathy
Dysregulation of MDA5 contributes to neuronal damage through various mechanisms including chronic neuroinflammation, increased interferon response, and glial activation.
Therapeutic Targeting
MDA5 represents an important therapeutic target. Multiple drug development programs are exploring strategies to modulate its function:
- MDA5 agonists: Antiviral immunotherapy
- MDA5 antagonists: For Aicardi-Goutières syndrome
- Modulation approaches: Targeting downstream signaling
External Links
- UniProt: [https://www.uniprot.org/uniprot/Q9QZF5](https://www.uniprot.org/uniprot/Q9QZF5)
- AlphaFold: [MDA5 Protein](https://alphafold.ebi.ac.uk/entry/Q9QZF5)
- PDB: [3GA6](https://www.rcsb.org/structure/3GA6), [4GL2](https://www.rcsb.org/structure/4GL2), [5W5V](https://www.rcsb.org/structure/5W5V)
See Also
- [Proteins Index](/proteins)
- [Genes Index](/genes)
- [Diseases Index](/diseases)
- [Mechanisms Index](/mechanisms)
- [RIG-I Protein](/proteins/rig-i-protein)
- [Innate Immunity](/mechanisms/innate-immunity)
Brain Atlas Resources
- Allen Human Brain Atlas: [MDA5 expression search](https://human.brain-map.org/microarray/search/show?search_term=IFIH1)
- Allen Mouse Brain Atlas: [MDA5 search](https://mouse.brain-map.org/search/index.html?query=IFIH1)
- Allen Cell Type Atlas: [Transcriptomic cell type reference](https://portal.brain-map.org/atlases-and-data/rnaseq)
Background
The study of Mda5 Protein 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.
References
[Andrejeva J, et al, (2004) (2004)](https://doi.org/10.1038/ni1087)
[Mott R, et al, (2016) (2016)](https://doi.org/10.1016/j.jmb.2016.02.008)
[Kang DC, et al, (2004) (2004)](https://doi.org/10.1073/pnas.0307803100)
[Kato H, et al, (2006) (2006)](https://doi.org/10.1038/nature04734)
[Rice GI, et al, (2014) (2014)](https://doi.org/10.1038/ng.2933)