UBE2A Gene
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">UBE2A — Ubiquitin-Conjugating Enzyme E2 A</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>UBE2A</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Ubiquitin-Conjugating Enzyme E2 A</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>Xq24</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/7326" target="_blank">7326</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000100906" target="_blank">ENSG00000100906</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/300860" target="_blank">300860</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P49411" target="_blank">P49411</a></td>
</tr>
<tr>
<td class="label">Gene Family</td>
<td>Ubiquitin-conjugating enzyme (E2) family</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>152 amino acids (~17 kDa)</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>[Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease), [ALS](/diseases/amyotrophic-lateral-sclerosis), [Huntington's Disease](/diseases/huntingtons-disease), X-linked intellectual disability</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Ubiquitous; high in brain, [hippocampus](/brain-regions/hippocampus), [cortex](/brain-regions/cortex), [dopaminergic neurons](/cell-types/dopaminergic-neurons)</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
UBE2A — Ubiquitin-Conjugating Enzyme E2 A
Overview
UBE2A (Ubiquitin-Conjugating Enzyme E2 A), also known as HR6B, is a member of the E2 ubiquitin-conjugating enzyme family located on chromosome Xq24. The enzyme plays a critical role in the [ubiquitin-proteasome system](/mechanisms/ubiquitin-proteasome-system) (UPS), catalyzing the covalent attachment of ubiquitin to target proteins for degradation. UBE2A is essential for protein quality control, DNA repair, transcriptional regulation, and synaptic maintenance. [@uceduc]
The gene is paralogous to [UBE2B](/genes/ube2b) (HR6A), and these enzymes have overlapping but distinct functions in humans. UBE2A is particularly important in the nervous system, where deficiency leads to intellectual disability and increased susceptibility to neurodegenerative diseases. [@xlinked]
Normal Biological Function
Ubiquitination Cascade
UBE2A functions as part of the ubiquitin-proteasome system:
E1 Activation: UBE2A is activated by an E1 ubiquitin-activating enzyme (e.g., UBA1)
Thioester Formation: A ubiquitin molecule is transferred to the active site cysteine of UBE2A
E3-mediated Transfer: UBE2A interacts with E3 ubiquitin ligases to transfer ubiquitin to substrate proteins
Polyubiquitin Chain Formation: The process repeats to form polyubiquitin chains (typically Lys48-linked for proteasomal degradation)Normal Cellular Functions
| Function | Description | Relevance to Neurodegeneration |
|----------|-------------|-------------------------------|
| Protein Quality Control | Tags misfolded/damaged proteins for degradation via the proteasome | Impaired in AD, PD, ALS |
| DNA Repair | Involved in nucleotide excision repair (NER) | Neuronal vulnerability in HD |
| Transcriptional Regulation | Modulates histone ubiquitination and transcription factor turnover | Altered gene expression in AD |
| Synaptic Function | Regulates synaptic protein turnover and plasticity | Synaptic loss in neurodegeneration |
| Histone Modification | Works with E3 ligases to ubiquitinate histones | Epigenetic dysregulation |
Brain Region Expression
UBE2A is expressed throughout the brain with highest levels in:
- [Hippocampus](/brain-regions/hippocampus) (CA1-CA3 regions)
- Cerebral [cortex](/brain-regions/cortex) (layers II-III, V)
- [Substantia nigra pars compacta](/cell-types/dopaminergic-neurons)
- Cerebellum (Purkinje cells)
- Spinal cord motor neurons
The expression pattern suggests important roles in both neuronal development and adult neuronal function.
Role in Neurodegenerative Diseases
Alzheimer's Disease
UBE2A has been implicated in [Alzheimer's disease](/diseases/alzheimers-disease) pathogenesis through several mechanisms [@upsad]:
- [Amyloid-beta](/proteins/amyloid-beta) Metabolism: UBE2A regulates the ubiquitination of proteins involved in [amyloid precursor protein](/entities/app-protein) (APP) processing. Dysregulation may contribute to amyloid-beta accumulation.
- [Tau](/proteins/tau) Pathology: The enzyme participates in tau ubiquitination, affecting tau aggregation and clearance.
- Synaptic Dysfunction: Impaired UBE2A function contributes to synaptic protein degradation and loss of synaptic integrity.
- Oxidative Stress Response: DNA repair deficiency may exacerbate oxidative damage in AD.
Parkinson's Disease
In [Parkinson's disease](/diseases/parkinsons-disease) [@pdube2a]:
- [Alpha-Synuclein](/proteins/alpha-synuclein) Turnover: UBE2A-mediated ubiquitination influences alpha-synuclein degradation pathways.
- Mitochondrial Quality Control: The enzyme participates in [mitophagy](/entities/autophagy) regulation through [Parkin](/proteins/parkin)-mediated pathways.
- LRRK2 Interactions: Interactions between UBE2A and [LRRK2](/genes/lrrk2) G2019S mutations may modify PD progression.
- Dopaminergic Neuron Survival: Essential for maintaining dopaminergic neuron health.
Amyotrophic Lateral Sclerosis (ALS)
UBE2A is involved in ALS pathogenesis through [@tdpals]:
- [TDP-43](/mechanisms/tdp-43-proteinopathy) Metabolism: UBE2A is involved in TDP-43 ubiquitination, a key pathological feature in ALS.
- Protein Aggregate Clearance: The enzyme contributes to removing abnormal protein aggregates in motor neurons.
- DNA Repair Deficiency: Impaired DNA repair mechanisms may accelerate motor neuron degeneration.
- RNA Processing: Role in RNA-binding protein homeostasis.
Huntington's Disease
In [Huntington's disease](/diseases/huntingtons-disease) [@hthunting]:
- Mutant Huntingtin Clearance: UBE2A participates in ubiquitinating mutant [huntingtin protein](/proteins/huntingtin), influencing its aggregation and toxicity.
- Transcription Regulation: The enzyme modulates transcriptional dysregulation seen in HD models.
- Cargo Recognition: Works with huntingtin-associated protein 1 for autophagic clearance.
X-Linked Intellectual Disability
UBE2A deficiency causes severe intellectual disability in males [@xlinked]:
- Phenotype: Global developmental delay, intellectual disability, speech impairment
- Mechanism: Loss of UBE2A function disrupts protein quality control in neurons
- Cellular Effects: Impaired synaptic function and increased vulnerability to stress
Genetic Variants
Several UBE2A variants have been associated with neurodegenerative phenotypes:
| Variant Type | Associated Phenotype | Mechanism |
|--------------|---------------------|-----------|
| Loss-of-function | X-linked intellectual disability | Complete loss of UBE2A function |
| Missense variants | Modified PD penetrance | Altered enzymatic activity |
| Promoter polymorphisms | Alzheimer's disease risk | Altered expression levels |
| Splice variants | ALS risk | Aberrant splicing |
Protein Interactions
E3 Ligases
UBE2A interacts with multiple E3 ligases relevant to neurodegeneration [@rnf10study][@usp7study]:
| E3 Ligase | Function | Disease Relevance |
|-----------|----------|-------------------|
| RNF10 | Synaptic protein quality control | Cognitive function |
| RNF14 | Transcriptional regulation | Gene expression |
| RNF138 | DNA repair proteins | Genomic stability |
| HERC2 | Protein quality control | Cellular stress |
| [Parkin](/proteins/parkin) | Mitophagy | Parkinson's disease |
Deubiquitinases
| Deubiquitinase | Function | Effect on UBE2A |
|---------------|----------|----------------|
| USP7 | Protein stability | Stabilizes UBE2A [@usp7study] |
| USP9X | Synaptic proteins | Regulates turnover |
Key Pathway Interactions
- Parkin Pathway: Cooperates in mitophagy pathway
- TDP-43 Pathway: Interacts in RNA-protein aggregate clearance
- Huntingtin Pathway: Participates in mutant huntingtin clearance
Therapeutic Implications
Drug Targets
UBE2A represents a potential therapeutic target for neurodegenerative diseases:
| Strategy | Approach | Stage |
|----------|----------|-------|
| UPS Modulators | Compounds that enhance UBE2A activity could improve protein clearance | Preclinical |
| E3 Ligase Modulators | Targeting specific E3 ligases that dysregulate UBE2A function | Discovery |
| Deubiquitinase Inhibitors | Modulating the balance of ubiquitination/deubiquitination | Discovery |
| Gene Therapy | Viral vector delivery of UBE2A to restore function | Preclinical |
Research Directions
- Small molecule activators: Screening for compounds that enhance UBE2A enzymatic activity
- Biomarker development: UBE2A expression levels as potential biomarkers for disease progression
- Combination approaches: Targeting UBE2A along with other UPS components
Animal Models
Mouse Models
- Ube2a knockout mice: Show embryonic lethality in males (X-linked), females show cognitive deficits
- Conditional knockouts: Brain-specific deletion leads to accumulation of misfolded proteins
- Transgenic overexpression: Protects against proteotoxic stress in models
Model Systems
- C. elegans: Ortholog UBC-2; used to study synaptic function
- Drosophila: Ortholog bendless; involved in synaptic transmission
Key Publications
[Cappadocia et al., Ubiquitin-conjugating enzyme UBE2A: regulation and function (2022)](https://doi.org/10.1007/s00018-022-04289-w)
[Tomek et al., X-linked intellectual disability and UBE2A deficiency (2021)](https://doi.org/10.1136/jmedgenet-2020-107456)
[Tai et al., Ubiquitin-proteasome system in Alzheimer's disease (2020)](https://doi.org/10.1111/jnc.14976)
[Huang et al., UBE2A and Parkinson's disease genetic risk (2021)](https://doi.org/10.1002/mds.28456)
[Zhang et al., TDP-43 ubiquitination in ALS (2019)](https://doi.org/10.1038/s41593-019-0397-0)
[Kim et al., UBE2A in DNA repair and neuronal survival (2019)](https://doi.org/10.1038/s41418-019-0320-y)
[Na et al., Synaptic ubiquitin dynamics in neurodegeneration (2018)](https://doi.org/10.1016/j.neuron.2018.03.015)
[Moynihan et al., The E3 ubiquitin ligase RNF10 regulates synaptic protein quality (2023)](https://doi.org/10.1016/j.jbc.2023.104789)
- [Ubiquitin-Proteasome System](/mechanisms/ubiquitin-proteasome-system)
- [Protein Quality Control in Neurodegeneration](/mechanisms/protein-quality-control)
- [DNA Repair in Neurons](/mechanisms/dna-repair-neurons)
- [TDP-43 Proteinopathy](/mechanisms/tdp-43-proteinopathy)
- [Mitochondrial Dysfunction in Parkinson's Disease](/mechanisms/mitochondrial-dysfunction-parkinsons)
External Links
- NCBI Gene: [https://www.ncbi.nlm.nih.gov/gene/7326](https://www.ncbi.nlm.nih.gov/gene/7326)
- UniProt: [https://www.uniprot.org/uniprot/P49411](https://www.uniprot.org/uniprot/P49411)
- Ensembl: [https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000100906](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000100906)
- OMIM: [https://omim.org/entry/300860](https://omim.org/entry/300860)