GO:0003847 1-alkyl-2-acetylglycerophosphocholine esterase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0003847 describes the enzymatic activity that hydrolyzes 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF) to 1-O-alkyl-sn-glycero-3-phosphocholine (lyso-PAF) and acetate, a key step in inactivating platelet-activating factor.
• The activity is best known as PAF acetylhydrolase or lipoprotein-associated phospholipase A2 (Lp-PLA2), encoded by the PLA2G7 gene in humans.
• Lp-PLA2/PAF-AH is secreted by macrophages and associates with LDL and HDL, where it hydrolyzes oxidized phospholipids and PAF, linking lipid metabolism to inflammation.
• Dysregulated PAF-AH activity is implicated in silicosis, pre-eclampsia, diabetic kidney disease, and tumor immunosuppression, making it a therapeutic target [1,3,5,7].
• Caloric restriction in humans alters immunometabolic regulators including PAF-AH, suggesting a role in health span.
• CRISPR-based knockout, point mutation, and knock-in models are essential to dissect the causal roles of PLA2G7 and related genes in disease.
Description
1-alkyl-2-acetylglycerophosphocholine esterase activity (GO:0003847) is a molecular function that catalyzes the hydrolysis of platelet-activating factor (PAF) and related acetylated phospholipids. This activity removes the acetyl group from the sn-2 position of PAF, producing lyso-PAF and acetate, thereby terminating the potent pro-inflammatory signaling of PAF. The enzyme responsible for this activity is often called PAF acetylhydrolase (PAF-AH) or lipoprotein-associated phospholipase A2 (Lp-PLA2), which is encoded by the PLA2G7 gene. Researchers study this activity because it sits at the intersection of lipid metabolism, inflammation, and immune regulation, with implications for diseases ranging from atherosclerosis to cancer [1,5]. The reaction is also relevant to macrophage biology, where PAF-AH modulates the production of bioactive lipids. Understanding GO:0003847 provides a framework for investigating how cells control inflammatory lipid mediators and how this control goes awry in disease.
1-alkyl-2-acetylglycerophosphocholine esterase activity At A Glance
| GO ID | GO:0003847 |
|---|---|
| GO term | 1-alkyl-2-acetylglycerophosphocholine esterase activity |
| Ontology | molecular_function |
| Synonym | PAF acetylhydrolase activity; lipoprotein-associated phospholipase A2 activity; LDL-associated phospholipase A2; 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine acetylhydrolase activity |
| Major function | Hydrolysis of PAF to lyso-PAF and acetate, inactivating a potent pro-inflammatory lipid mediator |
| Substrate | 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF) |
| Products | 1-O-alkyl-sn-glycero-3-phosphocholine (lyso-PAF), acetate, H+ |
| Cellular location | Secreted; associated with lipoproteins (LDL, HDL) in plasma |
| Representative gene | PLA2G7 (human), also known as Lp-PLA2 |
What Is GO:0003847?
According to the Gene Ontology, GO:0003847 is defined as the catalysis of the reaction: a 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine + H2O = 1-O-alkyl-sn-glycero-3-phosphocholine + acetate + H+. In simpler terms, it is an esterase that cleaves the acetyl group from the sn-2 position of PAF, converting it to lyso-PAF and releasing acetate. This activity is synonymous with PAF acetylhydrolase, PAF 2-acylhydrolase, and lipoprotein-associated phospholipase A2 (Lp-PLA2).
Why Is 1-alkyl-2-acetylglycerophosphocholine esterase activity Important in Cell Biology?
GO:0003847 is important because it controls the levels of platelet-activating factor (PAF), a phospholipid mediator with powerful pro-inflammatory and vasoactive effects. By hydrolyzing PAF, this activity prevents excessive inflammation and maintains vascular homeostasis. Dysregulation of PAF-AH has been linked to a wide range of pathological conditions, including silicosis, pre-eclampsia, diabetic kidney disease, and cancer [1,3,5,7]. Moreover, the enzyme's association with lipoproteins makes it a biomarker and potential therapeutic target for cardiovascular and metabolic diseases. Studying this activity helps researchers understand how lipid signaling is terminated and how its failure contributes to chronic inflammation.
• Terminates PAF signaling, a central pathway in inflammation and allergy.
• Modulates oxidized phospholipids on LDL and HDL, influencing atherosclerosis.
• Involved in macrophage activation and polarization.
• Linked to silicosis through profibrotic monocyte-derived macrophages.
• Altered in pre-eclampsia, affecting maternal and fetal plasma.
• Contributes to endothelial ferroptosis in diabetic kidney disease.
• Plays a role in tumor immunosuppression in hepatocellular carcinoma.
• Regulated by caloric restriction in humans, impacting health span.
• Potential target for mastocytosis treatment strategies.
• Essential for understanding lipid mediator balance in immune responses.
Molecular Mechanism of 1-alkyl-2-acetylglycerophosphocholine esterase activity
Substrate recognition and binding
In simple terms: The enzyme grabs PAF and positions it for cutting.
The enzyme recognizes the 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF) substrate through a hydrophobic binding pocket that accommodates the long alkyl chain at the sn-1 position and the acetyl group at sn-2. The choline headgroup is stabilized by electrostatic interactions. This binding specificity ensures that PAF and structurally related oxidized phospholipids are preferentially hydrolyzed.
Catalytic hydrolysis
In simple terms: Water is used to break the ester bond, releasing acetate.
The catalytic mechanism involves a serine hydrolase triad (Ser-His-Asp) that activates a water molecule for nucleophilic attack on the carbonyl carbon of the acetyl group. This leads to the formation of a tetrahedral intermediate, followed by release of acetate and the lyso-PAF product. The reaction is calcium-independent and occurs at the lipid-water interface.
Product release and downstream effects
In simple terms: The products leave the enzyme and can be used in other pathways.
After hydrolysis, lyso-PAF and acetate are released. Lyso-PAF can be re-acetylated to regenerate PAF or further metabolized. The removal of PAF terminates its signaling through the PAF receptor, thereby dampening inflammatory responses. This step is critical for resolving inflammation.
Regulation by lipoproteins and cellular context
In simple terms: The enzyme's activity is influenced by where it is and what it binds to.
Lp-PLA2/PAF-AH circulates in plasma primarily associated with LDL and HDL particles. This association modulates its substrate accessibility and activity. In macrophages, the enzyme can be secreted and act locally. Inflammatory cytokines and caloric restriction can alter its expression and activity [1,2].
Key Genes Involved in GO:0003847 1-alkyl-2-acetylglycerophosphocholine esterase activity
The following genes and proteins are directly or indirectly associated with 1-alkyl-2-acetylglycerophosphocholine esterase activity, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| PLA2G7 | Encodes Lp-PLA2/PAF-AH, the primary enzyme with this activity | Target in silicosis, cancer, and cardiovascular disease [1,5] |
| PAFAH1B1 | Encodes a subunit of intracellular PAF acetylhydrolase | Related to brain development and lissencephaly |
| PAFAH1B2 | Encodes a catalytic subunit of intracellular PAF-AH | Potential role in lipid metabolism |
| PAFAH1B3 | Encodes a catalytic subunit of intracellular PAF-AH | Potential role in lipid metabolism |
| PAFAH2 | Encodes a PAF acetylhydrolase with broad substrate specificity | Involved in oxidative stress responses |
| G2A | Lipid receptor that modulates inflammatory responses | Linked to macrophage activation |
| LYPLA1 | Lysophospholipase that may influence lyso-PAF levels | Indirectly affects PAF metabolism |
| LYPLA2 | Lysophospholipase with similar functions | Indirectly affects PAF metabolism |
| PLA2G4A | Cytosolic phospholipase A2, produces lyso-PAF precursor | Upstream of PAF synthesis |
| PLA2G4B | Phospholipase A2 family member | Potential role in lipid signaling |
| PLA2G4C | Phospholipase A2 family member | Potential role in lipid signaling |
| PLA2G4D | Phospholipase A2 family member | Potential role in lipid signaling |
| PLA2G4E | Phospholipase A2 family member | Potential role in lipid signaling |
| PLA2G4F | Phospholipase A2 family member | Potential role in lipid signaling |
| LPCAT1 | Lysophosphatidylcholine acyltransferase, may re-acylate lyso-PAF | Regulates PAF recycling |
| LPCAT2 | Lysophosphatidylcholine acyltransferase, may re-acylate lyso-PAF | Regulates PAF recycling |
| CHKA | Choline kinase, involved in phosphatidylcholine synthesis | Indirectly affects PAF levels |
How Is 1-alkyl-2-acetylglycerophosphocholine esterase activity Regulated?
The activity of 1-alkyl-2-acetylglycerophosphocholine esterase is regulated at multiple levels. Expression of PLA2G7, the gene encoding Lp-PLA2, is modulated by inflammatory cytokines and metabolic status; caloric restriction in humans has been shown to alter circulating levels of immunometabolic regulators including PAF-AH. The enzyme's activity is also influenced by its association with lipoproteins, which can either enhance or restrict substrate access. In macrophages, PAF-AH secretion is regulated during activation, and the lipid receptor G2A can modulate inflammatory responses that intersect with PAF signaling. Additionally, lysophospholipases may influence the availability of lyso-PAF, indirectly affecting the balance of this activity.
1-alkyl-2-acetylglycerophosphocholine esterase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PLA2G7 | Silicosis; profibrotic macrophages | Knockout mouse or macrophage-specific KO |
| PLA2G7 | Hepatocellular carcinoma; immunosuppression | Tumor xenograft with PLA2G7 KO macrophages |
| PLA2G7 | Diabetic kidney disease; endothelial ferroptosis | Endothelial cell-specific KO in diabetic mice |
| PAFAH1B1 | Lissencephaly; brain development | Conditional KO in neural progenitors |
| PLA2G7 | Pre-eclampsia; maternal-fetal plasma | Placental trophoblast overexpression |
Silicosis and fibrotic lung disease
In silicosis, Lp-PLA2 (encoded by PLA2G7) is upregulated in profibrotic monocyte-derived macrophages. Targeting Lp-PLA2 inhibits these macrophages by restoring cardiolipin-mediated mitophagy, suggesting that PAF-AH activity contributes to fibrosis progression.
Pre-eclampsia
Maternal and fetal plasma PAF acetylhydrolase activity is altered in pre-eclampsia, indicating a role for this enzyme in the pathophysiology of the disorder. Changes in PAF-AH activity may affect placental vascular function and maternal-fetal lipid homeostasis.
Diabetic kidney disease
Activation of the Lp-PLA2/LPC axis triggers endothelial ferroptosis, driving diabetic kidney disease. This links PAF-AH activity to oxidative stress and endothelial cell death in diabetes.
Cancer and immunosuppression
Inhibiting PLA2G7 reverses the immunosuppressive function of intratumoral macrophages and augments immunotherapy response in hepatocellular carcinoma. Thus, PAF-AH activity in the tumor microenvironment can promote immune evasion.
From 1-alkyl-2-acetylglycerophosphocholine esterase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of PLA2G7 affect PAF levels and inflammation? | PLA2G7 knockout cell line (e.g., THP-1 macrophages) |
| Does a specific point mutation in the catalytic triad abolish activity? | Point mutation knock-in (e.g., S273A) in PLA2G7 |
| Does tagging endogenous PLA2G7 reveal its localization? | Knock-in of fluorescent tag (e.g., GFP) at the PLA2G7 locus |
| Does overexpression of PLA2G7 alter tumor immune microenvironment? | PLA2G7 overexpression in cancer cells or macrophages |
| Which genes regulate PAF-AH activity? | CRISPR library screening in macrophage cell lines |
| Can we rescue the phenotype by re-expressing wild-type PLA2G7? | Knock-in of wild-type PLA2G7 into KO background |
How to Study the 1-alkyl-2-acetylglycerophosphocholine esterase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| PAF-AH activity assay | Enzymatic hydrolysis of PAF | Quantifying activity in cell lysates or plasma |
| Lipidomics (LC-MS) | PAF and lyso-PAF levels | Assessing substrate/product balance |
| RNA-seq | PLA2G7 and related gene expression | Transcriptional profiling in disease models |
| Western blot | Lp-PLA2 protein levels | Validating knockout or overexpression |
| Immunohistochemistry | Tissue localization of Lp-PLA2 | Analyzing expression in patient samples |
| CRISPR knockout | Loss-of-function phenotypes | Determining causal role of PLA2G7 |
| CRISPR knock-in | Tagged or mutant protein expression | Studying localization or catalytic mutants |
| Flow cytometry | Macrophage polarization markers | Linking PAF-AH to immune cell states |
Enzymatic activity assays
PAF acetylhydrolase activity is typically measured using radiolabeled or fluorescent PAF analogs, monitoring the release of acetate or lyso-PAF. These assays can be performed on cell lysates, plasma, or purified enzyme preparations [1,3].
Lipidomics and mass spectrometry
Mass spectrometry-based lipidomics allows quantification of PAF and lyso-PAF levels in biological samples, providing a direct readout of PAF-AH activity in cells and tissues [1,6].
Gene expression analysis
RNA-seq and qPCR are used to measure PLA2G7 mRNA levels in response to stimuli or genetic perturbations. This helps link transcriptional regulation to enzymatic activity [2,5].
CRISPR-based genetic screens
Genome-wide CRISPR knockout or activation screens can identify genes that regulate PAF-AH activity or PAF-induced phenotypes, enabling discovery of novel pathway components.
How CRISPR Can Be Used to Study GO:0003847 1-alkyl-2-acetylglycerophosphocholine esterase activity
Knockout
CRISPR knockout of PLA2G7 in macrophage cell lines or primary cells abolishes PAF-AH activity, allowing researchers to study the consequences for PAF accumulation, inflammation, and macrophage function. This approach has been used to show that Lp-PLA2 inhibition reverses immunosuppression in hepatocellular carcinoma models.
Point Mutation
Introducing point mutations in the catalytic triad of PLA2G7 (e.g., serine to alanine) via CRISPR knock-in creates enzyme-dead variants. These models help distinguish catalytic activity from non-enzymatic functions of the protein.
Knock-in
Knock-in of fluorescent tags (e.g., GFP) or epitope tags at the endogenous PLA2G7 locus enables real-time tracking of protein localization and secretion. Knock-in of disease-associated variants can also model human genetic risk.
Overexpression
CRISPR activation or lentiviral overexpression of PLA2G7 increases PAF-AH activity, which can be used to test whether elevated enzyme levels protect against or exacerbate inflammatory diseases. Overexpression in tumor cells has been used to study immune evasion.
How EDITGENE Supports 1-alkyl-2-acetylglycerophosphocholine esterase activity Research
Researchers studying 1-alkyl-2-acetylglycerophosphocholine esterase activity-related genes often need to determine whether a candidate gene is causally involved in a specific phenotype, such as PAF degradation, macrophage polarization, or disease progression. EDITGENE provides a comprehensive suite of CRISPR-based services to enable such investigations with precision and reproducibility.
Contact EDITGENE today to design your custom CRISPR model for 1-alkyl-2-acetylglycerophosphocholine esterase activity research.
Frequently Asked Questions About 1-alkyl-2-acetylglycerophosphocholine esterase activity
What is 1-alkyl-2-acetylglycerophosphocholine esterase activity?
It is the enzymatic activity that hydrolyzes PAF to lyso-PAF and acetate, encoded by GO:0003847. It is also known as PAF acetylhydrolase or Lp-PLA2.
What genes are involved in 1-alkyl-2-acetylglycerophosphocholine esterase activity?
The primary gene is PLA2G7, which encodes Lp-PLA2. Other related genes include PAFAH1B1, PAFAH1B2, PAFAH1B3, and PAFAH2.
What diseases are associated with PAF acetylhydrolase activity?
It has been linked to silicosis, pre-eclampsia, diabetic kidney disease, and cancer immunosuppression [1,3,5,7].
How is PAF-AH activity measured?
It is typically measured using enzymatic assays with radiolabeled or fluorescent PAF analogs, or by lipidomics to quantify PAF and lyso-PAF.
What is the difference between PAF-AH and Lp-PLA2?
They are often the same enzyme; Lp-PLA2 is the lipoprotein-associated form of PAF acetylhydrolase, encoded by PLA2G7.
Can CRISPR be used to study PAF-AH activity?
Yes, CRISPR knockout, point mutation, and knock-in models are powerful tools to dissect the function of PLA2G7 and related genes.
What is the role of PAF-AH in inflammation?
It inactivates PAF, a potent pro-inflammatory lipid, thereby dampening inflammatory responses.
Is PAF-AH activity related to caloric restriction?
Yes, caloric restriction in humans alters immunometabolic regulators including PAF-AH, suggesting a role in health span.
What cell types express PAF-AH?
It is secreted by macrophages and other cells, and circulates in plasma associated with lipoproteins.
How does PAF-AH contribute to cancer?
In hepatocellular carcinoma, inhibiting PLA2G7 reverses the immunosuppressive function of intratumoral macrophages, enhancing immunotherapy response.
Conclusion
1-alkyl-2-acetylglycerophosphocholine esterase activity (GO:0003847) is a critical enzymatic function that controls the levels of platelet-activating factor and related oxidized phospholipids. Its dysregulation is implicated in a spectrum of inflammatory, metabolic, and malignant diseases. Understanding its mechanism and regulation offers opportunities for therapeutic intervention. CRISPR-based models are indispensable for causally linking PLA2G7 and related genes to disease phenotypes, and EDITGENE provides the tools to accelerate such research.
References
- 1. Li S et al.. 2025. Targeting Lp-PLA2 inhibits profibrotic monocyte-derived macrophages in silicosis through restoring cardiolipin-mediated mitophagy.. Cell Mol Immunol 22(7):776-790 PMID: 40389600
- 2. Spadaro O et al.. 2022. Caloric restriction in humans reveals immunometabolic regulators of health span.. Science 375(6581):671-677 PMID: 35143297
- 3. Fan P et al.. 2012. Maternal and fetal plasma platelet-activating factor acetylhydrolase activity and distribution in pre-eclampsia.. Pediatr Res 72(4):426-31 PMID: 22797139
- 4. Li Q et al.. 2021. Lipid Receptor G2A-Mediated Signal Pathway Plays a Critical Role in Inflammatory Response by Promoting Classical Macrophage Activation.. J Immunol 206(10):2338-2352 PMID: 33941654
- 5. Zhang F et al.. 2024. Inhibiting PLA2G7 reverses the immunosuppressive function of intratumoral macrophages and augments immunotherapy response in hepatocellular carcinoma.. J Immunother Cancer 12(1) PMID: 38272562
- 6. Nakagawa Y et al.. 1992. Possible influence of lysophospholipase on the production of 1-acyl-2-acetylglycerophosphocholine in macrophages.. Biochim Biophys Acta 1126(3):277-85 PMID: 1637856
- 7. Zhou Y et al.. 2025. Activation of the Lp-PLA2/LPC axis triggers endothelial ferroptosis to drive diabetic kidney disease.. Free Radic Biol Med 241:818-828 PMID: 40983197
- 8. Siebenhaar F et al.. 2014. Treatment strategies in mastocytosis.. Immunol Allergy Clin North Am 34(2):433-47 PMID: 24745685
