EIF2α Protein

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EIF2α Protein

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">EIF2α Protein</th>
</tr>
<tr>
<td class="label">Kinase</td>
<td>Stress Signal</td>
</tr>
<tr>
<td class="label">PERK (EIF2AK3)</td>
<td>ER stress/unfolded proteins</td>
</tr>
<tr>
<td class="label">GCN2 (EIF2AK4)</td>
<td>Amino acid starvation</td>
</tr>
<tr>
<td class="label">PKR (EIF2AK2)</td>
<td>Viral dsRNA</td>
</tr>
<tr>
<td class="label">HRI (EIF2AK1)</td>
<td>Heme deficiency/oxidative stress</td>
</tr>
<tr>
<td class="label">Interactor</td>
<td>Relationship</td>
</tr>
<tr>
<td class="label">[PERK](/proteins/ire1)</td>
<td>Phosphorylates Ser51</td>
</tr>
<tr>
<td class="label">GCN2</td>
<td>Phosphorylates Ser51</td>
</tr>
<tr>
<td class="label">PKR</td>
<td>Phosphorylates Ser51</td>
</tr>
<tr>
<td class="label">HRI</td>
<td>Phosphorylates Ser51</td>
</tr>
<tr>
<td class="label">eIF2B</td>
<td>Target of p-EIF2α</td>
</tr>
<tr>
<td class="label">GADD34/PP1</td>
<td>Dephosphorylates Ser51</td>
</tr>
<tr>
<td class="label">ATF4</td>
<td>Translation enhanced</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/fibrosis" style="color:#ef9a9a">Fibrosis</a></td>
</tr>

...

EIF2α Protein

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EIF2α 
Eukaryotic Translation Initiation Factor 2 Subunit Alpha
<hr>
Symbol: EIF2S1 / EIF2A 
UniProt: [P05198](https://www.uniprot.org/uniprot/P05198) 
Gene: [EIF2S1](/entities/eif2s1) 
Molecular Weight: 36.1 kDa 
Location: Cytoplasm 
PDB: [3DW2](https://www.rcsb.org/structure/3DW2), [1KL9](https://www.rcsb.org/structure/1KL9)
</div>

Overview

Eukaryotic translation initiation factor 2 subunit alpha (EIF2α) is the regulatory subunit of the eIF2 heterotrimeric GTPase complex, which controls the rate-limiting step of protein synthesis initiation. Phosphorylation of EIF2α at Ser51 serves as the central hub for the integrated stress response (ISR), coordinating translational attenuation in response to diverse cellular stresses including ER stress, amino acid deprivation, viral infection, and oxidative damage[@wek2018].

In neurodegenerative diseases, aberrant EIF2α phosphorylation contributes to synaptic dysfunction, memory impairment, and neuronal death. The EIF2α pathway represents a major therapeutic target for Alzheimer's disease, Parkinson's disease, Huntington's disease, ALS, and prion disorders[@ma2020].

Structure and Domains

EIF2α contains:

N-terminal domain (1-185): Contains the critical Ser51 phosphorylation site within a flexible loop; interacts with GTP-binding subunit
Central β-barrel domain (186-280): Provides structural scaffold
C-terminal OB-fold domain (281-315): Mediates interactions with eIF2β and eIF2γ subunits

The eIF2 complex delivers initiator methionyl-tRNA (Met-tRNAi) to the 40S ribosomal subunit in a GTP-dependent manner. GTP hydrolysis and GDP release are required for each translation initiation cycle[@hinnebusch2014].

Normal Function

Translation Initiation

eIF2•GTP•Met-tRNAi ternary complex formation is essential for every round of translation initiation. The complex:

Binds the 40S ribosomal subunit

Scans mRNA 5' UTRs for start codons

Enables AUG start codon recognition

GTP hydrolysis releases eIF2-GDP for recycling

Integrated Stress Response (ISR)

Four kinases phosphorylate EIF2α at Ser51 in response to distinct stressors[@donnelly2013]:

Phosphorylated EIF2α (p-EIF2α) inhibits eIF2B, the GTP exchange factor, reducing ternary complex availability and global protein synthesis by 50-90%[@pakoszebrucka2016].

Selective Translation

Paradoxically, p-EIF2α enhances translation of specific mRNAs with upstream open reading frames (uORFs), including:

ATF4: Transcription factor activating stress response genes
CHOP (DDIT3): Pro-apoptotic transcription factor
GADD34: PPP1R15A, feedback phosphatase regulatory subunit

Role in Neurodegeneration

Alzheimer's Disease

In AD brains, elevated p-EIF2α and ATF4 levels correlate with disease progression[@hoozemans2007]:

PERK activation: Accumulation of misfolded [Aβ](/proteins/amyloid-beta) and [tau](/proteins/tau) activates the [UPR](/entities/unfolded-protein-response)
Synaptic plasticity: p-EIF2α impairs [long-term potentiation](/mechanisms/long-term-potentiation) (LTP) and memory consolidation
[BACE1](/entities/bace1) translation: Paradoxically, p-EIF2α increases BACE1 via uORF bypass, enhancing Aβ production
Neuronal death: Sustained CHOP expression promotes [apoptosis](/entities/apoptosis)

eIF2α phosphorylation is elevated in hippocampal [neurons](/entities/neurons) of AD patients and [APP](/entities/app-protein)/PS1 transgenic mice[@oconnor2008].

Parkinson's Disease

[α-synuclein](/proteins/alpha-synuclein) aggregates activate PERK in dopaminergic neurons
PINK1/Parkin dysfunction impairs mitochondrial protein quality control, triggering ER stress
Dopaminergic vulnerability: Substantia nigra neurons show elevated p-PERK and p-EIF2α

Post-mortem PD brains show increased p-PERK and p-EIF2α in surviving dopaminergic neurons[@hoozemans2005].

Huntington's Disease

PolyQ-expanded [huntingtin](/proteins/huntingtin) disrupts ER homeostasis
Chronic UPR activation contributes to striatal neuron degeneration
BDNF translation: p-EIF2α impairs dendritic BDNF synthesis, affecting synaptic plasticity

ALS and FTD

[TDP-43](/mechanisms/tdp-43-proteinopathy) cytoplasmic aggregates activate the ISR
[C9orf72](/entities/c9orf72) dipeptide repeats induce ER stress
SOD1 mutations trigger PERK activation in motor neurons
FUS pathology associated with PERK-p-EIF2α signaling

Prion Diseases

PrP^Sc accumulation activates PERK and PKR
Sustained p-EIF2α critical for prion neurotoxicity
ISRIB rescues prion-induced synaptic deficits in models

Therapeutic Targeting

ISRIB (Integrated Stress Response Inhibitor)

ISRIB stabilizes eIF2B, restoring translation despite p-EIF2α[@sidrauski2013]:

Mechanism: Binds eIF2B, counteracts p-EIF2α-mediated inhibition
Preclinical: Improves memory, protects neurons in AD/PD/HD models
Clinical: Not yet in human trials for neurodegeneration

PERK Inhibitors

GSK2606414: Potent PERK inhibitor, neuroprotective in prion and tau models
GSK2656157: Improved brain penetration
Limitations: Pancreatic toxicity due to essential PERK function in secretory cells

GCN2 Inhibitors

A-92: Selective GCN2 inhibitor
Potential: May reduce ISR in specific contexts

Salubrinal

Mechanism: Inhibits GADD34/PP1 phosphatase, sustaining p-EIF2α
Paradox: Protective in some models, harmful in others
Interpretation: Context-dependent; acute vs chronic activation

Key Interactions

External Links

[UniProt: P05198](https://www.uniprot.org/uniprot/P05198)
[PDB structures](https://www.rcsb.org/search?q=uniprot:P05198)

References

[Wek RC. Role of eIF2α kinases in translational control and adaptation to cellular stress. Cold Spring Harb Perspect Biol. 2018;10(7):a032861, https://doi.org/10.1101/cshperspect.a032861 (2018)](https://doi.org/10.1101/cshperspect.a032861](https://doi.org/10.1101/cshperspect.a032861](https://doi.org/10.1101/cshperspect.a032861)

[Ma T et al. Dysregulation of the eIF2α kinase PERK in neurodegeneration. Brain Res. 2020;1742:146907, https://doi.org/10.1016/j.brainres.2020.146907 (2020)](https://doi.org/10.1016/j.brainres.2020.146907](https://doi.org/10.1016/j.brainres.2020.146907](https://doi.org/10.1016/j.brainres.2020.146907)

[Hinnebusch AG. The scanning mechanism of eukaryotic translation initiation. Annu Rev Biochem. 2014;83:779-812, https://doi.org/10.1146/annurev-biochem-060713-035802 (2014)](https://doi.org/10.1146/annurev-biochem-060713-035802](https://doi.org/10.1146/annurev-biochem-060713-035802](https://doi.org/10.1146/annurev-biochem-060713-035802)

[Donnelly N et al. The eIF2α kinases: their structures and functions. Cell Mol Life Sci. 2013;70(19):3493-3511, https://doi.org/10.1007/s00018-012-1252-6 (2013)](https://doi.org/10.1007/s00018-012-1252-6](https://doi.org/10.1007/s00018-012-1252-6](https://doi.org/10.1007/s00018-012-1252-6)

[Pakos-Zebrucka K et al. The integrated stress response. EMBO Rep. 2016;17(10):1374-1395, https://doi.org/10.15252/embr.201642195 (2016)](https://doi.org/10.15252/embr.201642195](https://doi.org/10.15252/embr.201642195](https://doi.org/10.15252/embr.201642195)

[Hoozemans JJM et al. Activation of the unfolded protein response in Parkinson's disease. Biochem Biophys Res Commun. 2007;354(3):707-711, https://doi.org/10.1016/j.bbrc.2006.12.169 (2007)](https://doi.org/10.1016/j.bbrc.2006.12.169](https://doi.org/10.1016/j.bbrc.2006.12.169](https://doi.org/10.1016/j.bbrc.2006.12.169)

[O'Connor T et al. Phosphorylation of translation initiation factor eIF2α increases BACE1 levels. Neurobiol Aging. 2008;29(1):113-123, https://doi.org/10.1016/j.neurobiolaging.2006.08.012 (2008)](https://doi.org/10.1016/j.neurobiolaging.2006.08.012](https://doi.org/10.1016/j.neurobiolaging.2006.08.012](https://doi.org/10.1016/j.neurobiolaging.2006.08.012)

[Hoozemans JJM et al. The unfolded protein response is activated in pretangle neurons in Alzheimer's disease hippocampus. Am J Pathol. 2005;166(4):1281-1291, https://doi.org/10.1016/S0002-9440(10)62314-0 (2005)](https://doi.org/10.1016/S0002-9440(10)

[Sidrauski C et al. Pharmacological brake-release of mRNA translation enhances cognitive memory. eLife. 2013;2:e00498, https://doi.org/10.7554/eLife.00498 (2013)](https://doi.org/10.7554/eLife.00498](https://doi.org/10.7554/eLife.00498](https://doi.org/10.7554/eLife.00498)

Pathway Diagram

Mermaid diagram (expand to render)

Pathway Diagram

The following diagram shows the key molecular relationships involving EIF2α Protein discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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EIF2α Protein

EIF2α Protein

EIF2α Protein

Overview

Structure and Domains

Normal Function

Translation Initiation

Integrated Stress Response (ISR)

Selective Translation

Role in Neurodegeneration

Alzheimer's Disease

Parkinson's Disease

Huntington's Disease

ALS and FTD

Prion Diseases

Therapeutic Targeting

ISRIB (Integrated Stress Response Inhibitor)

PERK Inhibitors

GCN2 Inhibitors

Salubrinal

Key Interactions

See Also

External Links

References

Pathway Diagram

Pathway Diagram