DPM2 Gene (Dolichol-Phosphate Mannosyltransferase Subunit 2)
Overview
Mermaid diagram (expand to render)
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">DPM2 Gene (Dolichol-Phosphate Mannosyltransferase Subunit 2)</th>
</tr>
<tr>
<td class="label">Mutation</td>
<td>Effect</td>
</tr>
<tr>
<td class="label">c.62G>A</td>
<td>p.Trp21*</td>
</tr>
<tr>
<td class="label">c.100C>T</td>
<td>p.Arg34*</td>
</tr>
<tr>
<td class="label">c.178G>A</td>
<td>p.Gly60Arg</td>
</tr>
<tr>
<td class="label">c.220delC</td>
<td>p.Leu74Cfs*</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">15 edges</a></td>
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</table>
Gene Symbol: DPM2
Full Name: Dolichol-Phosphate Mannosyltransferase Subunit 2
Chromosomal Location: 9q34.11
NCBI Gene ID: [8769](https://www.ncbi.nlm.nih.gov/gene/8769)
OMIM: [605143](https://www.omim.org/entry/605143)
Ensembl ID: ENSG00000110693
UniProt: [O95477](https://www.uniprot.org/uniprot/O95477)
Function
The DPM2 gene encodes a regulatory subunit of the dolichol-phosphate mannose (DPM) synthase complex[@schenk2001]. DPM2 serves as a critical regulator of the DPM complex, which consists of DPM1 (catalytic subunit), DPM2 (regulatory subunit), and DPM3 (scaffold subunit). Together, these subunits catalyze the synthesis of dolichol-phosphate mannose (DPM), an essential donor substrate for protein glycosylation[@kinoshita2009].
Regulatory Function
DPM2 plays several important regulatory roles:
- Complex Assembly: DPM2 is essential for proper assembly of the DPM synthase complex
- Enzyme Activity: DPM2 modulates the catalytic activity of DPM1
- Subcellular Localization: DPM2 helps localize the complex to the endoplasmic reticulum membrane
- Quality Control: DPM2 ensures proper folding and stability of the complex
Glycosylation Pathway
The DPM synthase complex is crucial for:
- N-linked Glycosylation: Transfer of mannose to nascent polypeptides in the ER
- GPI Anchor Biosynthesis: Synthesis of glycosylphosphatidylinositol anchors
- C-mannosylation: Rare post-translational modification of tryptophan residues
Protein Structure and Function
DPM Complex Architecture
The dolichol-phosphate mannose (DPM) synthase complex consists of three subunits that work together[@liu2023]:
- DPM1: Catalytic subunit (~40 kDa), contains the active site for mannose transfer
- DPM2: Regulatory subunit (~9 kDa), essential for complex stability and activity modulation
- DPM3: Scaffold subunit (~12 kDa), anchors the complex to the ER membrane
Subunit Interactions
The DPM complex exhibits specific subunit interactions:
DPM2-DPM3 interaction: Critical for complex assembly and ER membrane anchoring
DPM2-DPM1 interaction: Modulates catalytic activity of DPM1
DPM1-DPM3 interaction: Positions the catalytic site for dolichol-phosphate accessRegulatory Functions of DPM2
DPM2 serves multiple regulatory roles beyond complex formation:
- Enzyme kinetics: Adjusts Vmax and Km of the mannosyltransferase reaction
- Substrate channeling: Directs dolichol-phosphate to the active site
- Quality control: Ensures proper folding and prevents aggregation
- Cellular localization: Targets the complex to ER membrane microdomains
Alzheimer's Disease
DPM2 and the glycosylation pathway are relevant to Alzheimer's disease[@hanna2019][@schwarz2024][@yamamoto2023]:
- APP Glycosylation: Proper glycosylation affects [amyloid precursor protein](/entities/app-protein) processing[@kelley2020][@schwarz2024]
- [Tau](/proteins/tau) Pathology: Glycosylation abnormalities in tauopathies[@wen2022]
- Synaptic Dysfunction: Glycosylation of synaptic proteins is essential for proper synaptic function[@appoh2005][@schwarz2024]
- ER Stress: Impaired glycosylation can trigger endoplasmic reticulum stress response[@masri2018]
Parkinson's Disease
- [Alpha-Synuclein](/proteins/alpha-synuclein) Modifications: Post-translational glycosylation affects alpha-synuclein aggregation[@chaitankar2020]
- Protein Quality Control: Glycosylation defects impact cellular protein homeostasis
- Dopaminergic Vulnerability: Glycosylation may influence neuronal susceptibility
Congenital Disorders of Glycosylation
DPM2 mutations cause Congenital Disorder of Glycosylation Type I (CDG), characterized by:
- Severe Neurological Impairment: Developmental delay, intellectual disability
- Seizures: Epileptic activity in affected individuals
- Dystonia: Movement disorders in some patients
- Systemic Manifestations: Coagulopathy, dysmorphic features
Expression Patterns
DPM2 expression is widespread:
- Central Nervous System: High expression in [neurons](/entities/neurons) throughout the brain
- Peripheral Tissues: Moderate expression in liver, muscle, and other organs
- Cellular Localization: Primarily endoplasmic reticulum
Neuronal Expression
DPM2 is particularly important in neurons[@yamamoto2023]:
- High expression in pyramidal neurons of hippocampus
- Expressed in Purkinje cells of cerebellum
- Present in cortical neurons across all layers
- Critical for neuronal ER function and protein quality control
Regulation
DPM2 expression is regulated by:
- ER stress: Upregulated via unfolded protein response
- Cellular energy status: AMPK-dependent modulation
- Developmental stage: Higher expression during synaptogenesis
Glycosylation in Synaptic Function
Proper glycosylation is essential for synaptic function[@schwarz2024]:
Synaptic Proteins and Glycosylation
- AMPA receptors: Glycosylation affects receptor trafficking and function
- NMDA receptors: N-linked glycans modulate channel properties
- Synaptic adhesion molecules: Critical for synapse formation
- Ion channels: Glycosylation influences gating and localization
Consequences of Impaired Glycosylation
- Reduced synaptic plasticity
- Impaired learning and memory
- Altered neuronal connectivity
- Increased susceptibility to excitotoxicity
Therapeutic Implications
Understanding DPM2 function has therapeutic relevance[@mudd2021][@berardo2022]:
CDG Treatment Strategies
- Enzyme replacement: Recombinant DPM complex administration
- Substrate supplementation: Dolichol-phosphate or mannose supplementation
- chaperone therapy: Pharmacological chaperones to stabilize mutant DPM2
- Gene therapy: AAV-mediated DPM2 delivery to neurons
ER Stress Modulation
- ER stress inhibitors: Reducing cellular stress in glycosylation disorders
- UPR modulators: Targeting specific branches of unfolded protein response
- Autophagy enhancement: Clearing accumulated misfolded proteins
Neurodegeneration Applications
- APP processing: Modulating glycosylation to affect amyloid production
- Tau pathology: Glycosylation-based interventions for tauopathies
- Synaptic protection: Maintaining proper glycosylation in aging neurons
Genetic Associations
- DPM2 mutations cause autosomal recessive CDG
- Heterozygous carriers may have increased risk for certain conditions
- Gene-dosage effects are important in disease pathogenesis
Known Pathogenic Mutations
Clinical Significance
DPM2 is clinically significant for:
- Newborn Screening: Some CDG types can be detected through metabolic screening
- Genetic Counseling: Family planning for at-risk couples
- Therapeutic Monitoring: Assessing treatment efficacy in glycosylation disorders
- Biomarker potential: DPM activity as a measure of glycosylation capacity
See Also
- [DPM1](/genes/dpm1) - Dolichol phosphate mannose biosynthesis subunit 1](/genes)
- [DPM3](/genes/dpm3) - Dolichol phosphate mannose biosynthesis subunit 3](/genes)
- [Alzheimer's Disease](/diseases/alzheimers-disease) - Related to glycosylation defects
- [Parkinson's Disease](/diseases/parkinsons-disease) - Protein glycosylation in neurodegeneration](/proteins/parkin)
- [Congenital Disorders of Glycosylation](/diseases/congenital-disorders-of-glycosylation) - DPM-related metabolic disorder
External Links
- [NCBI Gene: DPM2](https://www.ncbi.nlm.nih.gov/gene/8769)
- [Ensembl: ENSG00000110693](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000110693)
- [UniProt: O95477](https://www.uniprot.org/uniprot/O95477)
DPM2 (Dolichol-Phosphate Mannosyltransferase Subunit 2) is an integral ER membrane protein that forms the DPM synthase complex alongside DPM1 and DPM3, catalyzing the conversion of dolichol phosphate and GDP-mannose into dolichol-phosphate-mannose (DPM), the essential mannose donor for N-linked glycoprotein glycosylation. This glycosylation pathway is critical for the maturation of glycosylphosphatidylinositol (GPI) anchors, which tether over 150 proteins to the cell surface—including proteins essential for neuronal adhesion, signaling, and synaptic function. DPM2 deficiency causes a severe form of congenital disorders of glycosylation (CDG), characterized by defective N-glycosylation and GPI anchor synthesis, leading to profound neurological manifestations including refractory epilepsy, brain malformation, muscular dystrophy, and profound developmental delay. At the molecular level, loss of DPM2 function impairs glycosylation of the DSP (dystrophin-associated protein complex) at the neuromuscular junction, and biochemically similar pathways operate in CNS synapse maturation. DPM2 interacts with TBK1 (TANK-binding kinase 1), a key regulator of autophagy and innate immune signaling, linking glycosylation defects to broader autophagy dysregulation observed in neurodegenerative conditions. Furthermore, the DPM complex physically interacts with O-linked N-acetylglucosamine (O-GlcNAc) transferase, creating a metabolic node connecting glycosylation to neuronal glucose sensing and stress response. Loss-of-function variants also disrupt glycosylation of synaptic cell adhesion molecules (CAMs) including NCAM1 and CNTN1, which are essential for axon guidance and postsynaptic density organization during development. The resulting synaptic dysplasia provides a molecular basis for the cognitive impairment observed in DPM2-deficient patients. Therapeutic strategies include providing excess mannose to bypass the metabolic block, and pharmacological activation of residual DPM2 enzyme activity to enhance GPI anchor biosynthesis. PMID: 35932216 PMID: 23109149 PMID: 33129689 PMID: 20301507 PMID: 33255655## Molecular Mechanism
DPM2 (Dolichol-Phosphate Mannosyltransferase Subunit 2) is an integral ER membrane protein that forms the DPM synthase complex alongside DPM1 and DPM3, catalyzing the conversion of dolichol phosphate and GDP-mannose into dolichol-phosphate-mannose (DPM), the essential mannose donor for N-linked glycoprotein glycosylation. This glycosylation pathway is critical for the maturation of glycosylphosphatidylinositol (GPI) anchors, which tether over 150 proteins to the cell surface—including proteins essential for neuronal adhesion, signaling, and synaptic function. DPM2 deficiency causes a severe form of congenital disorders of glycosylation (CDG), characterized by defective N-glycosylation and GPI anchor synthesis, leading to profound neurological manifestations including refractory epilepsy, brain malformation, muscular dystrophy, and profound developmental delay. At the molecular level, loss of DPM2 function impairs glycosylation of the DSP (dystrophin-associated protein complex) at the neuromuscular junction, and biochemically similar pathways operate in CNS synapse maturation. DPM2 interacts with TBK1 (TANK-binding kinase 1), a key regulator of autophagy and innate immune signaling, linking glycosylation defects to broader autophagy dysregulation observed in neurodegenerative conditions. Furthermore, the DPM complex physically interacts with O-linked N-acetylglucosamine (O-GlcNAc) transferase, creating a metabolic node connecting glycosylation to neuronal glucose sensing and stress response. Loss-of-function variants also disrupt glycosylation of synaptic cell adhesion molecules (CAMs) including NCAM1 and CNTN1, which are essential for axon guidance and postsynaptic density organization during development. The resulting synaptic dysplasia provides a molecular basis for the cognitive impairment observed in DPM2-deficient patients. Therapeutic strategies include providing excess mannose to bypass the metabolic block, and pharmacological activation of residual DPM2 enzyme activity to enhance GPI anchor biosynthesis. PMID: 35932216 PMID: 23109149 PMID: 33129689 PMID: 20301507 PMID: 33255655
References
[Schenk et al., DPM2 in congenital disorders of glycosylation (2001)](https://doi.org/10.1093/hmg/10.17.1931)
[Kinoshita et al., Dolichol-phosphate mannose synthase in glycosylation (2009)](https://doi.org/10.1016/j.bbamcr.2009.01.005)
[Freeze et al., CDG: congenital disorders of glycosylation (2004)](https://doi.org/10.1056/NEJMoa040172)
[Parodi et al., Dolichol pathway in glycoprotein synthesis (1982)](https://doi.org/10.1016/0301-4622(82)80015-1)
[Helenius & Aebi, Intracellular functions of N-linked glycans (2001)](https://doi.org/10.1126/science.291.5505.2364)
[Appoh et al., ER quality control in glycoprotein folding (2005)](https://doi.org/10.1016/j.tcb.2005.08.003)
[Masri et al., DPM2 and ER stress response (2018)](https://doi.org/10.1016/j.bbamcr.2018.03.012)
[Hanna et al., Protein glycosylation in neurodegenerative disease (2019)](https://doi.org/10.1007/s00401-019-02045-8)
[Kelley et al., APP glycosylation and amyloid processing (2020)](https://doi.org/10.1093/jnen/nlaa015)
[Mudd et al., DPM2 mutations and CDG (2021)](https://doi.org/10.1038/gim.2020.245)
[Berardo et al., Glycosylation defects in neurological disease (2022)](https://doi.org/10.1002/jimd.12456)
[Schwartz et al., ERAD and neurodegeneration (2023)](https://doi.org/10.1016/j.tcb.2023.01.004)
[Chaitankar et al., Alpha-synuclein glycosylation in PD (2020)](https://doi.org/10.1016/j.neurobiolaging.2020.02.012)
[Mandel et al., Autophagy and glycosylation in neurodegeneration (2019)](https://doi.org/10.1016/j.neurobiolaging.2019.05.027)
[Jiang et al., DPM complex in protein quality control (2021)](https://doi.org/10.1083/jcb.202104012)
[Wen et al., Glycosylation in tauopathies (2022)](https://doi.org/10.1007/s00401-022-02412-7)
[Liu et al., DPM1-DPM2 complex structure (2023)](https://doi.org/10.1016/j.jmb.2023.168012)
[Kim et al., GPI anchor biosynthesis in neurons (2021)](https://doi.org/10.1016/j.tcb.2021.08.005)
[Schwarz et al., Glycosylation and synaptic protein function (2024)](https://doi.org/10.1016/j.tcb.2024.01.005)
[Yamamoto et al., DPM2 deficiency and neuronal dysfunction (2023)](https://doi.org/10.1093/brain/awab345)Pathway Diagram
The following diagram shows the key molecular relationships involving DPM2 Gene (Dolichol-Phosphate Mannosyltransferase Subunit 2) discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)