EIF2S1 (eIF2α)
<div class="infobox infobox-gene">
<table>
<tr><th colspan="2">EIF2S1 Gene</th></tr>
<tr><td>Symbol</td><td><b>EIF2S1</b></td></tr>
<tr><td>Full Name</td><td>Eukaryotic Translation Initiation Factor 2 Subunit Alpha</td></tr>
<tr><td>Also Known As</td><td>eIF2α, EIF2A</td></tr>
<tr><td>Chromosomal Location</td><td>14q23.3</td></tr>
<tr><td>NCBI Gene ID</td><td><a href="https://www.ncbi.nlm.nih.gov/gene/1965" target="_blank">1965</a></td></tr>
<tr><td>OMIM</td><td><a href="https://omim.org/entry/603907" target="_blank">603907</a></td></tr>
<tr><td>Ensembl ID</td><td><a href="https://ensembl.org/Homo_sapiens/Gene/View?g=ENSG00000134001" target="_blank">ENSG00000134001</a></td></tr>
<tr><td>UniProt ID</td><td><a href="https://www.uniprot.org/uniprot/P05198" target="_blank">P05198</a></td></tr>
<tr><td>Associated Diseases</td><td>[Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), ALS, Huntington's disease, Vanishing White Matter Disease</td></tr>
</table>
</div>
Pathway Diagram
Mermaid diagram (expand to render)
Overview
EIF2S1 encodes the alpha subunit of eukaryotic translation initiation factor 2 (eIF2), a critical regulator of protein synthesis and the master integrator of cellular stress responses[@hinnebusch2014]. Phosphorylation of eIF2α at serine 51 converts eIF2 from a translation initiator into a potent inhibitor of protein synthesis, allowing cells to conserve resources during stress while selectively translating stress-responsive transcripts like ATF4[@wek2018].
Function
Translation Initiation
eIF2 is a heterotrimeric GTPase (αβγ) that delivers initiator methionyl-tRNA (Met-tRNAi) to the 40S ribosomal subunit as part of the 43S preinitiation complex[@hinnebusch2014]. The eIF2·GTP·Met-tRNAi ternary complex is essential for every round of translation initiation.
Integrated Stress Response (ISR)
When phosphorylated at Ser51, eIF2α transforms eIF2 into a competitive inhibitor of its guanine nucleotide exchange factor, eIF2B[@wek2018]. This sequesters eIF2B and blocks new ternary complex formation, causing a rapid but reversible global translation arrest while allowing selective translation of mRNAs with upstream open reading frames (uORFs), most notably [ATF4](/genes/atf4)[@harding2000].
Four eIF2α Kinases
Four distinct kinases phosphorylate eIF2α in response to different stressors[@donnelly2013]:
| Kinase | Stress Signal | Relevance to Neurodegeneration |
|--------|---------------|-------------------------------|
| PERK (EIF2AK3) | ER stress | Protein misfolding in AD, PD |
| PKR (EIF2AK2) | Viral infection, dsRNA | Neuroinflammation |
| GCN2 (EIF2AK4) | Amino acid deprivation | Metabolic stress |
| HRI (EIF2AK1) | Heme deficiency | Less CNS relevance |
Disease Associations
Alzheimer's Disease
Increased phospho-eIF2α is detected in AD brains and correlates with disease severity[@chang2002]. PERK activation and eIF2α phosphorylation contribute to synaptic dysfunction and memory deficits. The ISR inhibitor ISRIB restores memory in AD mouse models[@sidrauski2013].
Vanishing White Matter Disease (VWM)
Mutations in eIF2B subunits (not eIF2α itself) cause VWM, but the disease manifests through hypersensitivity to eIF2α phosphorylation, demonstrating the critical importance of this pathway in CNS white matter maintenance[@van2006].
Parkinson's Disease
[Alpha-synuclein](/proteins/alpha-synuclein) aggregation activates the [UPR](/entities/unfolded-protein-response) and eIF2α phosphorylation. PERK inhibitors show neuroprotection in PD models[@hetz2015].
ALS and FTD
[TDP-43](/mechanisms/tdp-43-proteinopathy) pathology correlates with eIF2α phosphorylation. ISR modulation is being explored as a therapeutic strategy[@wang2020].
Expression
EIF2S1 is ubiquitously expressed as an essential gene. Brain expression is high in [neurons](/entities/neurons) and glia, with particular sensitivity in oligodendrocytes (explaining VWM white matter vulnerability)[@van2006a].
Therapeutic Implications
ISRIB (Integrated Stress Response Inhibitor)
ISRIB reverses the effects of eIF2α phosphorylation by stabilizing eIF2B and restoring translation[@sidrauski2013]. It shows promise in AD, PD, and traumatic brain injury models but has poor brain penetration.
PERK Inhibitors
Small molecule PERK inhibitors (GSK2606414, GSK2656157) reduce eIF2α phosphorylation but cause pancreatic toxicity due to PERK's role in beta cells[@hetz2015].
eIF2α Phosphatase Activators
Agents that enhance GADD34/PPP1R15A-mediated eIF2α dephosphorylation are being explored.
See Also
- [PERK](/genes/eif2ak3) — ER stress kinase
- [ATF4](/genes/atf4) — ISR transcription factor
- [GADD34](/genes/ppp1r15a) — eIF2α phosphatase cofactor
- [Integrated Stress Response](/mechanisms/integrated-stress-response)
- [Endoplasmic Reticulum Stress](/mechanisms/endoplasmic-reticulum-stress)
- [Vanishing White Matter Disease](/diseases/vanishing-white-matter-disease)
External Links
- [NCBI Gene: EIF2S1](https://www.ncbi.nlm.nih.gov/gene/1965)
- [UniProt: P05198](https://www.uniprot.org/uniprot/P05198)
- [KEGG Pathway: Protein processing in ER](https://www.genome.jp/kegg/pathway/hsa/hsa04141.html)
References
[Hinnebusch AG, The scanning mechanism of eukaryotic translation initiation (2014)](https://doi.org/10.1146/annurev-biochem-060713-035802)
[Wek RC, Role of eIF2α kinases in translational control and adaptation to cellular stress (2018)](https://doi.org/10.1016/bs.ircmb.2018.01.002)
[Harding HP et al, Regulated translation initiation controls stress-induced gene expression in mammalian cells (2000)](https://doi.org/10.1016/S0092-8674(00)
[Donnelly N et al, The eIF2α kinases: their structures and functions (2013)](https://doi.org/10.1111/febs.12371)
[Chang RC et al, Phosphorylation of eIF2α in Alzheimer's disease and other neurodegenerative disorders (2002)](https://doi.org/10.1016/j.neuint.2002.08.013)
[Sidrauski C et al, Pharmacological brake-release of mRNA translation enhances cognitive memory (2013)](https://doi.org/10.7554/eLife.00498)
[van der Knaap MS et al, Vanishing white matter disease (2006)](https://doi.org/10.1016/S1474-4422(06)
[Hetz C et al, Targeting the unfolded protein response in disease (2015)](https://doi.org/10.1038/nrd.2015.156)
[Wang L et al, Targeting the integrated stress response in ALS and FTD (2020)](https://doi.org/10.1186/s12967-020-02542-2)
[van Kollenburg B et al, Regulation of protein synthesis in the brain of patients with VWM disease (2006)](https://doi.org/10.1111/j.1651-2227.2006.tb02383.x)Pathway Diagram
The following diagram shows the key molecular relationships involving EIF2S1 (eIF2α) discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)