GO:0004306 ethanolamine-phosphate cytidylyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004306 describes the molecular function of ethanolamine-phosphate cytidylyltransferase, which catalyzes the reaction CTP + ethanolamine phosphate = diphosphate + CDP-ethanolamine.
• This activity is the committed step in the CDP-ethanolamine branch of the Kennedy pathway for phosphatidylethanolamine (PE) biosynthesis.
• The enzyme is encoded by PCYT2 (also known as ET) and is highly conserved from yeast to humans.
• Loss of PCYT2 function impairs muscle health and accelerates ageing in mice, linking this activity to lipid homeostasis and tissue maintenance.
• In cancer, increased PCYT2 activity supports adaptation to metabolic stress and tumor cell survival.
• CRISPR-based knockout, point-mutation, knock-in, and overexpression models enable precise interrogation of PCYT2 function in health and disease.
Description
Ethanolamine-phosphate cytidylyltransferase activity (GO:0004306) is a molecular function that catalyzes the formation of CDP-ethanolamine from CTP and ethanolamine phosphate, releasing diphosphate. This reaction is the rate-limiting and committed step in the CDP-ethanolamine pathway, also known as the Kennedy pathway, which produces phosphatidylethanolamine (PE), a major phospholipid in mammalian membranes. The enzyme responsible for this activity is CTP:phosphoethanolamine cytidylyltransferase (Pcyt2/ET), a highly conserved protein that is essential for maintaining PE homeostasis. Researchers study GO:0004306 because PE is not only a structural lipid but also a precursor for phosphatidylcholine, glycosylphosphatidylinositol anchors, and lipid signaling molecules. Dysregulation of this activity has been implicated in metabolic stress adaptation in cancer, muscle ageing, and immune cell function. Understanding the molecular mechanism, regulation, and disease relevance of this enzyme provides opportunities for therapeutic intervention. This article synthesizes authoritative QuickGO data and peer-reviewed literature to provide a comprehensive overview of GO:0004306, including its catalytic mechanism, key genes, regulatory pathways, disease associations, and experimental models for research.
ethanolamine-phosphate cytidylyltransferase activity At A Glance
| GO ID | GO:0004306 |
|---|---|
| GO term | ethanolamine-phosphate cytidylyltransferase activity |
| Ontology | molecular_function |
| Synonym | CTP:ethanolamine-phosphate cytidylyltransferase activity; CTP-phosphoethanolamine cytidylyltransferase activity; CTP:phosphoethanolamine cytidylyltransferase activity; ET; ethanolamine phosphate cytidylyltransferase activity; phosphoethanolamine cytidylyltransferase activity; phosphorylethanolamine transferase activity |
| Major function | Catalyzes the formation of CDP-ethanolamine from CTP and ethanolamine phosphate, the committed step in phosphatidylethanolamine synthesis via the Kennedy pathway |
| Reaction | CTP + ethanolamine phosphate = diphosphate + CDP-ethanolamine |
| Enzyme class | Nucleotidyltransferase (EC 2.7.7.14) |
| Cellular location | Cytosol |
| Key gene | PCYT2 (ET) |
What Is GO:0004306?
Ethanolamine-phosphate cytidylyltransferase activity (GO:0004306) is defined as the catalysis of the reaction: CTP + ethanolamine phosphate = diphosphate + CDP-ethanolamine. In this reaction, the enzyme transfers a cytidylyl group from CTP to ethanolamine phosphate, producing CDP-ethanolamine and releasing pyrophosphate. This activity is synonymous with CTP:phosphoethanolamine cytidylyltransferase, phosphoethanolamine cytidylyltransferase, and phosphorylethanolamine transferase. It is a nucleotidyltransferase that belongs to the cytidylyltransferase family and is essential for phospholipid biosynthesis.
Why Is ethanolamine-phosphate cytidylyltransferase activity Important in Cell Biology?
GO:0004306 is critical because it governs the rate-limiting step of phosphatidylethanolamine (PE) biosynthesis through the CDP-ethanolamine pathway. PE is the second most abundant phospholipid in mammalian membranes and is essential for membrane integrity, cell division, and autophagy. The activity of this enzyme directly influences the availability of CDP-ethanolamine for PE synthesis, thereby affecting lipid homeostasis, energy metabolism, and cell survival under stress. Dysregulation of this activity has been linked to cancer metabolic reprogramming, muscle ageing, and immune disorders, making it a potential therapeutic target.
• Rate-limiting step in the CDP-ethanolamine pathway for phosphatidylethanolamine (PE) biosynthesis.
• Maintains membrane phospholipid balance and influences membrane curvature and fusion.
• Supports cancer cell adaptation to metabolic stress by increasing PE synthesis.
• Essential for muscle health and prevention of premature ageing in mice.
• Modulates T follicular helper cell responses and humoral immunity through PE metabolism.
• Implicated in hyperhomocysteinemia-aggravated glomerular injury via ferroptosis.
• Potential target for modulating autophagy and mitophagy in lymphoma.
• Provides CDP-ethanolamine for synthesis of glycosylphosphatidylinositol anchors and phosphatidylcholine.
• Enzyme activity can be regulated by CTP availability and feedback inhibition.
• Genetic variants in PCYT2 may affect lipid-related disorders and ageing.
Molecular Mechanism of ethanolamine-phosphate cytidylyltransferase activity
Substrate Binding and Catalysis
In simple terms: The enzyme grabs CTP and ethanolamine phosphate and joins them together, releasing pyrophosphate.
Ethanolamine-phosphate cytidylyltransferase binds its substrates, CTP and ethanolamine phosphate, in an ordered manner. The enzyme catalyzes the transfer of the cytidylyl group from CTP to the hydroxyl group of ethanolamine phosphate, forming CDP-ethanolamine and releasing diphosphate (pyrophosphate). This reaction is reversible in vitro but proceeds toward CDP-ethanolamine synthesis in vivo due to subsequent metabolic steps.
Cofactors and Metal Requirements
In simple terms: The enzyme does not need metal ions but requires magnesium for optimal activity.
Unlike some nucleotidyltransferases, ethanolamine-phosphate cytidylyltransferase does not strictly require divalent metal ions for catalysis, but magnesium ions can stimulate its activity. The enzyme uses CTP as the preferred nucleotide substrate, although other nucleoside triphosphates can substitute with lower efficiency.
Enzyme Structure and Oligomeric State
In simple terms: The enzyme is a single polypeptide that can form dimers or higher oligomers.
Pcyt2, the protein responsible for GO:0004306, is a cytosolic enzyme that exists as a homodimer or higher oligomer in solution. Each monomer contains a catalytic domain with conserved residues essential for substrate binding and catalysis. The enzyme lacks transmembrane domains and is not glycosylated.
Regulation by Lipids and Phosphorylation
In simple terms: The enzyme's activity can be turned up or down by lipids and chemical modifications.
Ethanolamine-phosphate cytidylyltransferase activity is regulated by the availability of its substrates and by feedback inhibition from downstream products such as CDP-ethanolamine and phosphatidylethanolamine. Additionally, phosphorylation of Pcyt2 by AMP-activated protein kinase (AMPK) may modulate its activity under metabolic stress. The enzyme can also be regulated at the transcriptional level in response to hormonal and nutritional signals.
Role in the Kennedy Pathway
In simple terms: This enzyme is the middle step in a three-step assembly line that makes a major membrane lipid.
GO:0004306 catalyzes the second step of the CDP-ethanolamine branch of the Kennedy pathway. Ethanolamine is first phosphorylated by ethanolamine kinase to ethanolamine phosphate, which is then converted to CDP-ethanolamine by this enzyme. Finally, CDP-ethanolamine:diacylglycerol ethanolaminephosphotransferase (CEPT1) transfers phosphoethanolamine to diacylglycerol to form phosphatidylethanolamine.
Key Genes Involved in GO:0004306 ethanolamine-phosphate cytidylyltransferase activity
The following genes and proteins are directly or indirectly involved in ethanolamine-phosphate cytidylyltransferase activity and its associated pathways.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PCYT2 (ET) | Encodes ethanolamine-phosphate cytidylyltransferase, the enzyme catalyzing GO:0004306 | Core enzyme; knockout causes embryonic lethality in mice; linked to muscle ageing |
| ETNK1 | Ethanolamine kinase; phosphorylates ethanolamine to ethanolamine phosphate | Provides substrate for PCYT2; mutations in ETNK1 found in leukemia |
| CEPT1 | CDP-ethanolamine:diacylglycerol ethanolaminephosphotransferase; final step of PE synthesis | Uses CDP-ethanolamine produced by PCYT2; regulates mitophagy in lymphoma |
| CHKA | Choline kinase; phosphorylates choline for phosphatidylcholine synthesis | Parallel pathway; balances PC/PE ratio |
| PCYT1A | CTP:phosphocholine cytidylyltransferase; rate-limiting for phosphatidylcholine synthesis | Homologous enzyme in the choline branch; shares regulatory features |
| PEMT | Phosphatidylethanolamine N-methyltransferase; converts PE to PC | Consumes PE produced via PCYT2; affects lipid homeostasis |
| PLA2G6 | Phospholipase A2; hydrolyzes PE to release arachidonic acid | Links PE metabolism to inflammation and ferroptosis |
| GPAT1 | Glycerol-3-phosphate acyltransferase; initiates glycerophospholipid synthesis | Provides diacylglycerol for CEPT1 in PE synthesis |
| LPCAT3 | Lysophosphatidylcholine acyltransferase; remodels PE | Affects PE saturation and membrane fluidity |
| AMPK | AMP-activated protein kinase; energy sensor | Phosphorylates and regulates PCYT2 under metabolic stress |
| mTOR | Mechanistic target of rapamycin; regulates lipid synthesis | Controls PCYT2 expression and PE synthesis in T cells |
| SREBP1 | Sterol regulatory element-binding protein 1; transcription factor | Regulates lipogenic genes including PCYT2 |
| PPARα | Peroxisome proliferator-activated receptor alpha | Regulates lipid metabolism genes; may influence PCYT2 expression |
| CTPS1 | CTP synthase 1; synthesizes CTP | Provides CTP for PCYT2 reaction; linked to lymphoma |
| BHMT | Betaine-homocysteine S-methyltransferase; affects homocysteine metabolism | Hyperhomocysteinemia alters PE metabolism and ferroptosis |
| CBS | Cystathionine beta-synthase; transsulfuration | Homocysteine levels affect lipid metabolism and PCYT2 activity |
| MTHFR | Methylenetetrahydrofolate reductase; folate cycle | Polymorphisms affect homocysteine and lipid homeostasis |
| GCLC | Glutamate-cysteine ligase catalytic subunit; glutathione synthesis | Ferroptosis sensitivity linked to PE oxidation |
How Is ethanolamine-phosphate cytidylyltransferase activity Regulated?
Ethanolamine-phosphate cytidylyltransferase activity is regulated at multiple levels. Transcriptionally, the PCYT2 gene is induced by SREBP1 and PPARα in response to lipid availability. Post-translationally, AMPK phosphorylates PCYT2 under energy stress, modulating its activity. The enzyme is also subject to feedback inhibition by CDP-ethanolamine and phosphatidylethanolamine, ensuring balanced phospholipid synthesis. In immune cells, mTOR signaling promotes PCYT2 expression to support PE synthesis during T follicular helper cell differentiation. Additionally, CTP availability from CTPS1 directly influences the reaction rate.
ethanolamine-phosphate cytidylyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PCYT2 | Muscle ageing and myopathy | Muscle-specific Pcyt2 knockout mouse; CRISPR KO in C2C12 myoblasts |
| PCYT2 | Breast cancer metabolic stress adaptation | PCYT2 knockout in MDA-MB-231 cells; overexpression in MCF-7 |
| CEPT1 | Diffuse large B-cell lymphoma | CEPT1 knockout in DLBCL cell lines; xenograft models |
| PCYT2 | T follicular helper cell differentiation and humoral immunity | Pcyt2 conditional knockout in CD4+ T cells; immunization models |
| PCYT2 | Hyperhomocysteinemia-aggravated glomerular injury | Pcyt2 heterozygous mice with high-methionine diet; ferroptosis inhibitors |
Cancer and Metabolic Stress
Cancer cells often reprogram lipid metabolism to support rapid proliferation. Breast cancer cells adapt to metabolic stress by increasing ethanolamine phospholipid synthesis and PCYT2 activity, which supports survival under hypoxia and nutrient deprivation. In diffuse large B-cell lymphoma, CTPS1 modulates mitophagy by reshaping CEPT1-mediated phospholipid metabolism, suggesting that PCYT2-derived CDP-ethanolamine is critical for lymphoma progression. Targeting this pathway may sensitize cancer cells to metabolic stress.
Muscle Ageing and Myopathy
PCYT2-regulated lipid biosynthesis is critical for muscle health and ageing. Muscle-specific knockout of Pcyt2 in mice leads to impaired muscle function, accelerated ageing, and reduced lifespan. This highlights the importance of ethanolamine-phosphate cytidylyltransferase activity in maintaining muscle membrane integrity and mitochondrial function.
Immune Regulation and Humoral Immunity
Phosphatidylethanolamine metabolism controlled by PCYT2 supports T follicular helper (TFH) cell responses and humoral immunity. Inhibition of PE synthesis impairs TFH cell differentiation and antibody production, linking GO:0004306 to immune disorders.
Kidney Injury and Ferroptosis
Hyperhomocysteinemia aggravates hypertensive glomerular lesions by triggering ferroptosis, a process dependent on PE oxidation. B cell-derived anti-beta 2 glycoprotein I antibodies mediate this effect, and altered PE metabolism may contribute to kidney injury.
From ethanolamine-phosphate cytidylyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of complete loss of PCYT2 on cell viability? | CRISPR knockout of PCYT2 in HEK293T or HeLa cells |
| How does a specific point mutation in the catalytic domain affect enzyme activity? | CRISPR point mutation (e.g., H89A) knock-in in PCYT2 locus |
| Does tagging PCYT2 with GFP affect its localization and function? | CRISPR knock-in of GFP tag at the endogenous PCYT2 locus |
| What is the impact of PCYT2 overexpression on lipid metabolism? | Lentiviral overexpression of PCYT2 in cancer cell lines |
| Which genes interact with PCYT2 in a synthetic lethal network? | CRISPR library screening in PCYT2-knockout cells |
| How does PCYT2 regulate muscle ageing in vivo? | Muscle-specific Pcyt2 knockout mouse generated by CRISPR |
| Can PCYT2 activity be modulated by small molecules? | Overexpression of PCYT2 in cell-based assays for high-throughput screening |
How to Study the ethanolamine-phosphate cytidylyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiometric enzyme assay | Catalytic activity of PCYT2 using [14C]ethanolamine phosphate | Kinetic studies and inhibitor screening |
| LC-MS/MS lipidomics | Phosphatidylethanolamine and CDP-ethanolamine levels | Assessing lipid changes in knockout or overexpression cells |
| CRISPR knockout screening | Genes essential for growth in PCYT2-mutant cells | Identifying synthetic lethal interactions |
| RNA-seq | Transcriptional changes upon PCYT2 manipulation | Pathway analysis and biomarker discovery |
| Western blot | Protein expression levels of PCYT2 and pathway enzymes | Validation of knockout or overexpression |
| Immunofluorescence | Subcellular localization of PCYT2 | Determining cytosolic distribution |
| Seahorse assay | Mitochondrial respiration and glycolysis | Metabolic phenotyping of PCYT2 mutants |
| Flow cytometry | Cell viability, apoptosis, and ferroptosis | Evaluating cell death mechanisms |
Enzymatic Activity Assays
Ethanolamine-phosphate cytidylyltransferase activity can be measured using radiometric assays with [14C]ethanolamine phosphate and CTP, followed by separation of CDP-ethanolamine by thin-layer chromatography or HPLC. Alternatively, a coupled enzyme assay using pyruvate kinase and lactate dehydrogenase can monitor ADP release if ATP is used instead of CTP.
Lipidomics and Mass Spectrometry
Changes in phosphatidylethanolamine and related phospholipids can be quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to assess the impact of PCYT2 manipulation on lipid homeostasis.
CRISPR Screening and Functional Genomics
Genome-wide CRISPR knockout or activation screens can identify genes that are synthetic lethal with PCYT2 loss or that regulate its expression. These screens are powerful for uncovering pathways that compensate for or depend on ethanolamine-phosphate cytidylyltransferase activity.
Imaging and Subcellular Localization
Fluorescence microscopy of GFP-tagged PCYT2 or immunofluorescence with specific antibodies can reveal its cytosolic localization and potential translocation under stress conditions.
How CRISPR Can Be Used to Study GO:0004306 ethanolamine-phosphate cytidylyltransferase activity
Knockout
CRISPR-Cas9 knockout of PCYT2 (ET) generates cell lines or animal models completely lacking ethanolamine-phosphate cytidylyltransferase activity. These models are essential for studying the loss-of-function phenotypes, such as impaired PE synthesis, growth defects, and metabolic stress sensitivity. Knockout mice exhibit embryonic lethality, highlighting the essential role of this enzyme.
Point Mutation
CRISPR point mutation can introduce specific amino acid substitutions in the catalytic domain of PCYT2 to dissect the mechanism of catalysis or to model human mutations. For example, mutating conserved residues involved in CTP binding can abolish enzyme activity without affecting protein stability.
Knock-in
CRISPR knock-in can be used to insert epitope tags (e.g., FLAG, GFP) or reporter genes at the endogenous PCYT2 locus, enabling real-time tracking of expression and localization. Knock-in of disease-associated variants can also model human genetic disorders.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of PCYT2 can elevate ethanolamine-phosphate cytidylyltransferase activity, which is useful for studying gain-of-function effects in cancer metabolic stress adaptation and lipid accumulation.
How EDITGENE Supports ethanolamine-phosphate cytidylyltransferase activity Research
Researchers studying ethanolamine-phosphate cytidylyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in lipid metabolism, cell survival, or disease progression. Precise genetic models are essential to establish direct links between PCYT2 function and phenotypes.
Contact EDITGENE today to design your custom CRISPR model for ethanolamine-phosphate cytidylyltransferase activity research.
Frequently Asked Questions About ethanolamine-phosphate cytidylyltransferase activity
What is ethanolamine-phosphate cytidylyltransferase activity?
It is the molecular function (GO:0004306) that catalyzes the conversion of CTP and ethanolamine phosphate to CDP-ethanolamine and diphosphate, a key step in phosphatidylethanolamine synthesis.
What genes are involved in ethanolamine-phosphate cytidylyltransferase activity?
The primary gene is PCYT2 (also known as ET), which encodes the enzyme. Other related genes include ETNK1, CEPT1, and CHKA.
What is the role of PCYT2 in cancer?
PCYT2 supports cancer cell adaptation to metabolic stress by increasing ethanolamine phospholipid synthesis, and its activity is elevated in breast cancer cells under stress. It also contributes to lymphoma progression via CEPT1-mediated phospholipid metabolism.
How is ethanolamine-phosphate cytidylyltransferase activity regulated?
It is regulated by substrate availability, feedback inhibition by CDP-ethanolamine and PE, transcriptional control by SREBP1 and PPARα, and phosphorylation by AMPK.
What diseases are associated with PCYT2 mutations?
PCYT2 mutations are linked to muscle ageing and myopathy, and altered activity is implicated in cancer, immune disorders, and kidney injury.
What is the reaction catalyzed by GO:0004306?
CTP + ethanolamine phosphate = diphosphate + CDP-ethanolamine.
How can I study ethanolamine-phosphate cytidylyltransferase activity in the lab?
You can use radiometric enzyme assays, LC-MS/MS lipidomics, CRISPR knockout/overexpression models, and CRISPR screening.
What are the synonyms for GO:0004306?
Synonyms include CTP:ethanolamine-phosphate cytidylyltransferase activity, phosphoethanolamine cytidylyltransferase activity, and phosphorylethanolamine transferase activity.
Is PCYT2 essential for survival?
Yes, knockout of Pcyt2 in mice causes embryonic lethality, indicating it is essential for development.
How does PCYT2 affect muscle ageing?
Muscle-specific loss of Pcyt2 leads to impaired muscle function and accelerated ageing, highlighting its role in maintaining muscle lipid homeostasis.
Conclusion
Ethanolamine-phosphate cytidylyltransferase activity (GO:0004306) is a fundamental molecular function in phospholipid metabolism, catalyzing the committed step of phosphatidylethanolamine synthesis via the Kennedy pathway. Its enzyme, PCYT2, is essential for membrane integrity, energy metabolism, and cell survival under stress. Dysregulation of this activity contributes to cancer progression, muscle ageing, immune dysfunction, and kidney injury. The availability of CRISPR-based models, lipidomics, and functional genomics tools now enables precise interrogation of PCYT2 in health and disease. Targeting this pathway holds promise for therapeutic intervention in metabolic and age-related disorders.
References
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- 2. Bladergroen BA et al.. 1997. CTP:phosphoethanolamine cytidylyltransferase.. Biochim Biophys Acta 1348(1-2):91-9 PMID: 9370320
- 3. Cikes D et al.. 2023. PCYT2-regulated lipid biosynthesis is critical to muscle health and ageing.. Nat Metab 5(3):495-515 PMID: 36941451
- 4. Du X et al.. 2023. B cell-derived anti-beta 2 glycoprotein I antibody mediates hyperhomocysteinemia-aggravated hypertensive glomerular lesions by triggering ferroptosis.. Signal Transduct Target Ther 8(1):103 PMID: 36907919
- 5. Shang C et al.. 2026. CTPS1 modulates mitophagy to propel diffuse large B-cell lymphoma via reshaping CEPT1-mediated phospholipid metabolism.. Redox Biol 92:104132 PMID: 41865720
- 7. Zhu L et al.. 2012. Breast cancer cells adapt to metabolic stress by increasing ethanolamine phospholipid synthesis and CTP:ethanolaminephosphate cytidylyltransferase-Pcyt2 activity.. Biochem Cell Biol 90(2):188-99 PMID: 22339418
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