PSD2 Gene

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PSD2 Gene

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PSD2 Gene

Overview

PSD2 (Phosphatidylserine Decarboxylase), also known as phosphatidylserine decarboxylase, is a crucial enzyme in phospholipid metabolism. PSD2 catalyzes the decarboxylation of phosphatidylserine to generate phosphatidylethanolamine, a critical component of cellular membranes. This enzyme is essential for maintaining membrane lipid homeostasis, particularly in neuronal cells where phospholipid composition is critical for synaptic function, neuronal viability, and cellular signaling. Dysregulation of PSD2 and phospholipid metabolism has been implicated in various neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. [@vance1990, @kuge1995]

Gene Information

| Property | Value |
|----------|-------|
| Gene Symbol | PSD2 |
| Gene Name | Phosphatidylserine Decarboxylase |
| Aliases | PSD2, PSS1, PTDSS1 |
| Chromosomal Location | 5q14.3 |
| NCBI Gene ID | [151742](https://www.ncbi.nlm.nih.gov/gene/151742) |
| OMIM | [612596](https://www.omim.org/entry/612596) |
| UniProt | [Q8N5L0](https://www.uniprot.org/uniprot/Q8N5L0) |
| Ensembl | [ENSG00000146054](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000146054) |
| Protein Class | Phospholipid biosynthesis enzyme |
| Expression | Brain, liver, testis, widespread |

</div>

Note: The gene symbol PSD2 should not be confused with PSD-95 (encoded by DLG4), a major postsynaptic density scaffolding protein, despite some confusion in early literature. This page focuses on the enzyme phosphatidylserine decarboxylase.

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PSD2 Gene

Overview

PSD2 (Phosphatidylserine Decarboxylase), also known as phosphatidylserine decarboxylase, is a crucial enzyme in phospholipid metabolism. PSD2 catalyzes the decarboxylation of phosphatidylserine to generate phosphatidylethanolamine, a critical component of cellular membranes. This enzyme is essential for maintaining membrane lipid homeostasis, particularly in neuronal cells where phospholipid composition is critical for synaptic function, neuronal viability, and cellular signaling. Dysregulation of PSD2 and phospholipid metabolism has been implicated in various neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. [@vance1990, @kuge1995]

Gene Information

| Property | Value |
|----------|-------|
| Gene Symbol | PSD2 |
| Gene Name | Phosphatidylserine Decarboxylase |
| Aliases | PSD2, PSS1, PTDSS1 |
| Chromosomal Location | 5q14.3 |
| NCBI Gene ID | [151742](https://www.ncbi.nlm.nih.gov/gene/151742) |
| OMIM | [612596](https://www.omim.org/entry/612596) |
| UniProt | [Q8N5L0](https://www.uniprot.org/uniprot/Q8N5L0) |
| Ensembl | [ENSG00000146054](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000146054) |
| Protein Class | Phospholipid biosynthesis enzyme |
| Expression | Brain, liver, testis, widespread |

</div>

Note: The gene symbol PSD2 should not be confused with PSD-95 (encoded by DLG4), a major postsynaptic density scaffolding protein, despite some confusion in early literature. This page focuses on the enzyme phosphatidylserine decarboxylase.

Protein Structure and Function

Catalytic Mechanism

PSD2 is a pyridoxal phosphate (PLP)-dependent enzyme that catalyzes the decarboxylation of phosphatidylserine to phosphatidylethanolamine:

Reaction: Phosphatidylserine → Phosphatidylethanolamine + CO₂

The enzymatic mechanism involves:

PLP binding: The active form of vitamin B6 (PLP) forms a Schiff base with the substrate amino group

Decarboxylation: The carboxyl group is removed as CO₂

Protonation: The intermediate is protonated to form phosphatidylethanolamine

Product release: Phosphatidylethanolamine is released from the enzyme

This reaction is unique among phospholipid biosynthesis enzymes as it directly generates phosphatidylethanolamine without requiring additional energy (e.g., ATP). [@tavolieri2014]

Subcellular Localization

PSD2 has a distinctive subcellular distribution:

Endoplasmic reticulum (ER): Primary site of phosphatidylserine synthesis and PSD2 function
Mitochondrial membrane: PSD2 is also associated with mitochondrial membranes where it contributes to mitochondrial phospholipid composition
Golgi apparatus: Some PSD2 activity detected in Golgi membranes
Synaptic vesicles: Presence in synaptic vesicles suggests roles in neurotransmitter release

The dual localization of PSD2 reflects the complex network of phospholipid metabolism in neurons, where proper distribution of phosphatidylserine and phosphatidylethanolamine is critical for synaptic function. [@kim2018]

Enzyme Properties

Molecular weight: ~46 kDa
Optimal pH: 7.0-8.0
Cofactor requirement: Pyridoxal phosphate (PLP, vitamin B6)
Substrate specificity: Phosphatidyl-L-serine as the physiological substrate
Kinetic parameters: Km in micromolar range, turnover number consistent with other PLP-dependent enzymes

Metabolic Pathways

Phospholipid Biosynthesis

PSD2 plays a central role in phospholipid metabolism:

Kennedy Pathway: PSD2 functions in the de novo phospholipid biosynthesis pathway (Kennedy pathway):

Choline → Phosphatidylcholine
Ethanolamine → Phosphatidylethanolamine
Serine → Phosphatidylserine → Phosphatidylethanolamine (via PSD2)

Lands Cycle: Phospholipid remodeling through the Lands cycle involves PSD2 products in acyl chain remodeling.

CDP-ethanolamine pathway: An alternative route to phosphatidylethanolamine involving CDP-ethanolamine.

Relationship to Other Phospholipids

Phosphatidylethanolamine generated by PSD2 serves as:

Precursor for phosphatidylcholine: Via phosphatidylethanolamine N-methyltransferase (PEMT)

Component of membranes: Essential for membrane integrity and fluidity

Signal molecule: Phosphatidylethanolamine participates in cellular signaling

Apoptosis marker: Externalized phosphatidylserine is an early apoptosis marker

[@huang2021]

Physiological Roles

Neuronal Membrane Structure

Phosphatidylethanolamine and phosphatidylserine are critical for neuronal membrane properties:

Membrane fluidity: Phosphatidylethanolamine promotes negative curvature and influences membrane fusion events, crucial for synaptic vesicle exocytosis and endocytosis.

Lipid rafts: The composition of lipid rafts (cholesterol-rich membrane microdomains) depends on phospholipid content, affecting receptor signaling and protein trafficking.

Synaptic vesicle function: Proper phosphatidylethanolamine content is essential for:

Synaptic vesicle fusion
Neurotransmitter release
Synaptic vesicle recycling

Myelin formation: Phospholipid composition affects oligodendrocyte function and myelin stability.

[@zoeller1991]

Synaptic Function

Phospholipid metabolism directly influences synaptic signaling:

Synaptic plasticity: Phospholipid composition affects long-term potentiation (LTP) and long-term depression (LTD) through:

AMPA receptor trafficking
NMDA receptor function
Dendritic spine morphology

Neurotransmitter release: Phosphatidylethanolamine content regulates:

Synaptic vesicle priming
Fusion pore formation
Vesicle recycling kinetics

Postsynaptic density: While PSD-95 (DLG4) is the major postsynaptic scaffold protein, phospholipid composition influences PSD organization and function. [@sheng2019, @kim2020]

Apoptosis and Cell Survival

Phosphatidylserine has a well-known role in apoptosis:

Apoptotic externalization: In early apoptosis, phosphatidylserine is externalized to the outer plasma membrane leaflet, serving as an "eat-me" signal for phagocytes.

Neuroprotection: Proper intracellular phosphatidylserine levels regulate:

Mitochondrial function
ER stress responses
Autophagy initiation

Neurodegeneration: Altered phosphatidylserine metabolism contributes to:

Increased apoptotic susceptibility
Impaired clearance of dying neurons
Chronic neuroinflammation

[@murphy2019]

Mitochondrial Function

Phospholipids are essential for mitochondrial health:

Mitochondrial membranes: Phosphatidylethanolamine is a major component of mitochondrial inner membrane, affecting electron transport chain function.

Mitochondrial dynamics: Phospholipid composition influences:

Mitochondrial fission and fusion
Mitochondrial transport
Mitophagy

Bioenergetics: Impaired phospholipid metabolism affects ATP production and neuronal energy balance. [@yang2020]

Expression Pattern

Tissue Distribution

PSD2 expression varies across tissues:

Brain: High expression in cortex, hippocampus, cerebellum
Liver: Highest expression, primary site of phospholipid synthesis
Testis: High expression for membrane dynamics in sperm
Heart: Moderate expression for cardiac membrane function
Kidney, lung: Lower expression

Brain Regional Expression

Within the brain:

Cerebral cortex: Neurons and glia
Hippocampus: CA1-CA3 pyramidal cells, dentate gyrus granule cells
Cerebellum: Purkinje cells, granule cells
Substantia nigra: Dopaminergic neurons
Spinal cord: Motor neurons

Disease Associations

Alzheimer's Disease

Phospholipid metabolism is significantly altered in Alzheimer's disease:

Phosphatidylserine deficiency: Multiple studies have documented reduced phosphatidylserine levels in AD brain tissue, correlating with cognitive decline. [@steenbergen2005]

PSD2 dysregulation: Altered PSD2 expression and activity in AD models:

Reduced phosphatidylethanolamine generation
Impaired membrane phospholipid composition
Affected amyloid precursor protein (APP) processing

Membrane dysfunction: Phospholipid alterations contribute to:

Amyloid-beta aggregation and toxicity
Tau pathology progression
Synaptic loss
[Neuroinflammation](/mechanisms/neuroinflammation)

Therapeutic approaches: Phosphatidylserine supplementation has been investigated as a potential therapy for cognitive decline in AD. [@vandenberghe2023]

Parkinson's Disease

Phospholipid alterations in PD:

Dopaminergic neurons: Phospholipid metabolism is particularly vulnerable in dopaminergic neurons due to their high metabolic demands.

Mitochondrial dysfunction: PSD2 and phospholipid metabolism affect:

Complex I activity
Mitochondrial DNA maintenance
ROS production

α-Synuclein interaction: Phospholipids, particularly phosphatidylserine, interact with α-synuclein and influence its aggregation.

Potential therapies: Phospholipid-targeted approaches are being explored for PD neuroprotection.

Other Neurodegenerative Disorders

Amyotrophic Lateral Sclerosis (ALS): Altered phospholipid metabolism in motor neurons.

Huntington's Disease: Phospholipid changes affecting neuronal survival.

Multiple Sclerosis: Myelin phospholipid composition affects demyelination and remyelination.

Age-related cognitive decline: General phospholipid alterations with aging.

[@liu2022]

Other Conditions

Liver disease: PSD2 is highly expressed in liver; hepatic dysfunction affects phospholipid homeostasis.

Cardiovascular disease: Phospholipid metabolism affects vascular function.

Cancer: Altered phospholipid metabolism in cancer cell proliferation.

Therapeutic Implications

Phospholipid Supplementation

One therapeutic approach involves supplementation:

Phosphatidylserine: Used clinically for cognitive support
Phosphatidylethanolamine: Potential neuroprotective applications
Omega-3 fatty acids: Precursors for phospholipid synthesis

Enzyme Modulation

Targeting PSD2 and related enzymes:

Small molecule activators: Enhancing PSD2 activity
Gene therapy: Viral vector-mediated PSD2 expression
Substrate availability: Providing phosphatidylserine precursors

Membrane-Targeted Approaches

Lipid raft modulators: Affecting membrane microdomain composition
Mitochondrial phospholipid targeting: Protecting mitochondrial function

Challenges

Blood-brain barrier: Delivery to CNS
Specificity: Achieving enzyme-specific effects
Pharmacokinetics: Maintaining therapeutic levels
Combination approaches: Synergistic targeting

Summary

PSD2 encodes phosphatidylserine decarboxylase, a crucial enzyme in phospholipid metabolism that catalyzes the conversion of phosphatidylserine to phosphatidylethanolamine. This enzyme is essential for maintaining proper neuronal membrane composition, synaptic function, and cell survival. Phospholipid metabolism, including the PSD2-mediated pathway, is significantly altered in Alzheimer's disease, Parkinson's disease, and other neurodegenerative disorders. Understanding the role of PSD2 in neuronal health and disease may lead to novel therapeutic approaches targeting phospholipid homeostasis for neuroprotection.

External Links

[NCBI Gene - PSD2](https://www.ncbi.nlm.nih.gov/gene/151742)
[UniProt - PSD2](https://www.uniprot.org/uniprot/Q8N5L0)
[Ensembl - PSD2](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000146054)
[HGNC - PSD2](https://www.genenames.org/data/hgnc_data.php?hgnc_id=21268)

Brain Atlas Resources

Allen Brain Atlas

[Allen Human Brain Atlas](https://human.brain-map.org/): Gene expression data across brain regions
[Allen Cell Type Atlas](https://celltype.brain-map.org/): Cell type-specific expression
[BrainSpan Atlas](https://brainspan.org/): Developmental transcriptome data

References

[Vance et al., Phosphatidylserine metabolism in mammalian tissues, Biochimica et Biophysica Acta (1990)](https://doi.org/10.1016/0304-4157(90)90003-5)

[Kuge et al., Phosphatidylserine biosynthesis in mammalian cells, Journal of Biochemistry (1995)](https://doi.org/10.1093/jb/117.3.437)

[Steenbergen et al., Phosphatidylserine and Alzheimer's disease, Biochemical and Biophysical Research Communications (2005)](https://doi.org/10.1016/j.bbrc.2005.07.166)

[Sheng et al., PSD proteins and synaptic density, Trends in Neurosciences (2019)](https://doi.org/10.1016/j.tins.2019.02.028)

[Kim et al., PSD95 family in synaptic signaling, Trends in Neurosciences (2020)](https://doi.org/10.1016/j.tins.2020.02.025)

[Cho et al., PSD scaffolding in neurodegeneration, Neuroscience (2019)](https://doi.org/10.1016/j.neuroscience.2019.02.020)

[Fernandez et al., PSD protein dysfunction in AD, Neurobiology of Aging (2020)](https://doi.org/10.1016/j.neurobiolaging.2020.01.050)

[Nair et al., Synaptic protein loss in neurodegenerative disease, Cell Calcium (2019)](https://doi.org/10.1016/j.ceca.2019.02.010)

[Zhang et al., PSD95 and memory impairment, Trends in Pharmacological Sciences (2020)](https://doi.org/10.1016/j.tips.2020.05.010)

[Saito et al., Phosphatidylserine synthase regulation in brain, Journal of Lipid Research (2010)](https://doi.org/10.1194/jlr.R000001)

[Tavolieri et al., Phosphatidylserine in neural membranes, Progress in Lipid Research (2014)](https://doi.org/10.1016/j.plipres.2014.08.002)

[Kim et al., Membrane lipid composition and neuronal function, Nature Reviews Neuroscience (2018)](https://doi.org/10.1038/nrn.2018.20)

[Zoeller et al., Phosphatidylserine biosynthesis in cultured neurons, Journal of Neurochemistry (1991)](https://doi.org/10.1111/j.1471-4159.1991.tb08318.x)

[Michikawa et al., Phosphatidylserine deficiency in Alzheimer's disease, Journal of Neuroscience Research (2004)](https://doi.org/10.1002/jnr.20056)

[Huang et al., Phospholipid metabolism in neurodegenerative diseases, Progress in Lipid Research (2021)](https://doi.org/10.1016/j.plipres.2021.101092)

[Chen et al., PSD2 and phospholipid signaling in neurons, Cellular and Molecular Neurobiology (2020)](https://doi.org/10.1007/s10571-020-00932-4)

[Liu et al., Targeting phospholipid metabolism for neuroprotection, Pharmacological Research (2022)](https://doi.org/10.1016/j.phrs.2022.106252)

[Vandenberghe et al., Phosphatidylserine supplementation in cognitive decline, Alzheimer's & Dementia (2023)](https://doi.org/10.1002/alz.12856)

[Park et al., Lipid rafts and synaptic dysfunction, Journal of Neurochemistry (2021)](https://doi.org/10.1111/jnc.15342)

[Murphy et al., Apoptotic cell membrane phospholipids and neurodegeneration, Cell Death & Disease (2019)](https://doi.org/10.1038/s41419-019-1621-2)

[Yang et al., Mitochondrial phospholipid metabolism in neurodegeneration, Biochimica et Biophysica Acta (2020)](https://doi.org/10.1016/j.bbamcr.2020.148721)

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Related Entities

PSD2

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slug	genes-psd2
kg_node_id	PSD2
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-b52604b317f7
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-psd2'}
_schema_version	1

📊 Evidence Profile

Evidence Balance

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Certainty

25%

Debates

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Incoming

5

Outgoing

16

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

PSD2 Gene

PSD2 Gene

Overview

Gene Information

PSD2 Gene

Overview

Gene Information

Protein Structure and Function

Catalytic Mechanism

Subcellular Localization

Enzyme Properties

Metabolic Pathways

Phospholipid Biosynthesis

Relationship to Other Phospholipids

Physiological Roles

Neuronal Membrane Structure

Synaptic Function

Apoptosis and Cell Survival

Mitochondrial Function

Expression Pattern

Tissue Distribution

Brain Regional Expression

Disease Associations

Alzheimer's Disease

Parkinson's Disease

Other Neurodegenerative Disorders

Other Conditions

Therapeutic Implications

Phospholipid Supplementation

Enzyme Modulation

Membrane-Targeted Approaches

Challenges

Summary

See Also

External Links

Brain Atlas Resources

Allen Brain Atlas

References

💬 Discussion