GO:0140333 glycerophospholipid flippase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0140333 glycerophospholipid flippase activity describes ATP-dependent movement of glycerophospholipids from the exoplasmic to the cytosolic leaflet of a membrane.
• Flippases are P4-ATPases that maintain asymmetric phospholipid distribution, which is essential for membrane integrity and signaling.
• Loss of flippase activity leads to phosphatidylserine exposure, a hallmark of apoptosis and platelet procoagulant activity [1,4].
• Flippases regulate endosomal phosphatidylserine, which is critical for YAP signaling in proliferating cells.
• Novel phosphatidylinositol flippases contribute to phosphoinositide homeostasis at the plasma membrane.
• Flippase activity is required for sperm activation during fertilization, as shown for TAT-5 in C. elegans.
Description
Glycerophospholipid flippase activity (GO:0140333) is a molecular function that catalyzes the ATP-dependent translocation of glycerophospholipids from the exoplasmic to the cytosolic leaflet of a membrane. This activity is essential for establishing and maintaining the asymmetric distribution of phospholipids across cellular membranes, a fundamental feature of eukaryotic cells. The asymmetric arrangement of lipids, with phosphatidylserine and phosphatidylethanolamine predominantly in the cytosolic leaflet and phosphatidylcholine and sphingomyelin in the exoplasmic leaflet, is critical for diverse cellular processes including apoptosis, blood coagulation, and signal transduction [1,2]. Researchers study glycerophospholipid flippases to understand how membrane lipid asymmetry is generated and how its disruption contributes to human diseases such as cancer and thrombosis [4,5]. The function is carried out by P4-ATPases, a subfamily of P-type ATPases that specifically transport phospholipids across the bilayer. Recent studies have expanded the known roles of flippases to include regulation of phosphoinositide homeostasis and cell signaling pathways [3,5].
glycerophospholipid flippase activity At A Glance
| GO ID | GO:0140333 |
|---|---|
| GO term | glycerophospholipid flippase activity |
| Ontology | molecular_function |
| Synonym | glycerophospholipid flippase activity (exoplasmic to cytosolic leaflet) |
| Major function | ATP-dependent translocation of glycerophospholipids from exoplasmic to cytosolic leaflet |
| Catalytic mechanism | P4-ATPase-mediated hydrolysis of ATP to drive lipid flipping |
| Substrates | Glycerophospholipids such as phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine |
| Cofactors | Magnesium ions, ATP |
| Regulation | By subunit proteins such as CDC50 family members |
What Is GO:0140333?
Glycerophospholipid flippase activity (GO:0140333) is defined as the catalysis of the movement of a glycerophospholipid from the exoplasmic to the cytosolic leaflet of a membrane, using energy from the hydrolysis of ATP. This activity is synonymous with glycerophospholipid flippase activity (exoplasmic to cytosolic leaflet). It is a molecular function that ensures the asymmetric distribution of phospholipids, which is crucial for membrane stability and cellular signaling.
Why Is glycerophospholipid flippase activity Important in Cell Biology?
Glycerophospholipid flippase activity is fundamental for maintaining membrane lipid asymmetry, which is critical for cell survival, signaling, and host-pathogen interactions. Disruption of this activity leads to exposure of phosphatidylserine on the cell surface, a signal for apoptotic cell clearance and blood coagulation [1,4]. Flippases also regulate endosomal phosphatidylserine, which is required for YAP signaling and cell proliferation. Moreover, flippase activity is essential for sperm activation during fertilization. Understanding this activity provides insights into diseases such as cancer, thrombosis, and infertility [4,5,7].
• Maintains asymmetric phospholipid distribution essential for membrane integrity.
• Regulates apoptosis by controlling phosphatidylserine exposure.
• Modulates blood coagulation through platelet procoagulant activity.
• Supports YAP signaling and cell proliferation via endosomal phosphatidylserine.
• Contributes to phosphoinositide homeostasis at the plasma membrane.
• Required for sperm activation and fertilization.
• Involved in cardiolipin synthesis and mitochondrial function.
• Potential target for reducing thrombin generation in thrombosis.
• Linked to cancer cell proliferation through YAP pathway.
• Essential for normal development and tissue homeostasis.
Molecular Mechanism of glycerophospholipid flippase activity
Substrate Recognition and Binding
In simple terms: The flippase enzyme recognizes and binds specific lipids on the outer side of the membrane.
Glycerophospholipid flippases, primarily P4-ATPases, selectively bind glycerophospholipids such as phosphatidylserine and phosphatidylethanolamine in the exoplasmic leaflet. Substrate specificity is determined by the transmembrane domain and associated subunits like CDC50 proteins. This binding is the first step before ATP hydrolysis drives lipid translocation.
ATP Hydrolysis and Conformational Change
In simple terms: The enzyme uses ATP energy to change its shape and flip the lipid across the membrane.
Upon substrate binding, the P4-ATPase hydrolyzes ATP, leading to phosphorylation of the catalytic aspartate residue and a conformational change that moves the lipid through the membrane. This process is similar to other P-type ATPases but specialized for lipid substrates. The energy from ATP hydrolysis is essential for the unidirectional transport from exoplasmic to cytosolic leaflet.
Lipid Translocation and Release
In simple terms: The lipid is moved to the inner side of the membrane and released.
Following the conformational change, the glycerophospholipid is translocated across the bilayer and released into the cytosolic leaflet. This maintains the asymmetric distribution of lipids, with phosphatidylserine and phosphatidylethanolamine enriched in the cytosolic leaflet. The flippase then returns to its original conformation to complete the cycle.
Regulation by Subunits and Cofactors
In simple terms: Other proteins and ions help control the flippase activity.
P4-ATPases require accessory subunits, such as CDC50 family proteins, for proper folding, localization, and activity. Magnesium ions are necessary for ATP hydrolysis. Additionally, flippase activity can be regulated by phosphorylation and interactions with other proteins. Recent studies have identified novel phosphatidylinositol flippases that contribute to phosphoinositide homeostasis.
Key Genes Involved in GO:0140333 glycerophospholipid flippase activity
The following genes encode proteins that exhibit glycerophospholipid flippase activity or regulate it.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ATP8A1 | P4-ATPase flippase for phosphatidylserine | Neuronal function, membrane asymmetry |
| ATP8A2 | P4-ATPase flippase for phosphatidylserine | Cerebellar degeneration, hearing loss |
| ATP8B1 | P4-ATPase flippase for phosphatidylserine | Cholestasis, liver disease |
| ATP8B2 | P4-ATPase flippase | Phospholipid transport |
| ATP9A | P4-ATPase flippase | Endosomal trafficking |
| ATP9B | P4-ATPase flippase | Sperm activation |
| ATP10A | P4-ATPase flippase | Glucose metabolism, obesity |
| ATP10B | P4-ATPase flippase | Parkinson's disease |
| ATP10D | P4-ATPase flippase | Lipid metabolism |
| ATP11A | P4-ATPase flippase for phosphatidylserine | Apoptosis, blood coagulation [1,4] |
| ATP11B | P4-ATPase flippase | Endosomal phosphatidylserine, YAP signaling |
| ATP11C | P4-ATPase flippase for phosphatidylserine | B cell development, anemia |
| CDC50A | Accessory subunit for P4-ATPases | Flippase maturation and activity |
| CDC50B | Accessory subunit for P4-ATPases | Flippase maturation and activity |
| CDC50C | Accessory subunit for P4-ATPases | Flippase maturation and activity |
| TAT-5 | P4-ATPase flippase in C. elegans | Sperm activation for fertilization |
| CLS1 | Cardiolipin synthase | Cardiolipin flipping |
| PIS1 | Phosphatidylinositol synthase | Phosphoinositide homeostasis |
How Is glycerophospholipid flippase activity Regulated?
Glycerophospholipid flippase activity is regulated at multiple levels. P4-ATPases require association with CDC50 family subunits for proper folding and transport to the plasma membrane. Phosphorylation of the flippase can modulate its activity. Additionally, the lipid environment and membrane composition influence flippase function. In platelets, maintaining flippase activity is a novel approach to reducing thrombin generation, indicating that regulation of flippase activity is critical for hemostasis. Endosomal phosphatidylserine, regulated by flippases, is critical for YAP signaling in proliferating cells.
glycerophospholipid flippase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ATP11A | Thrombosis, apoptosis | Knockout platelets, thrombin generation assays |
| ATP11B | Cancer, YAP signaling | Knockout cancer cell lines, YAP reporter assays |
| ATP8B1 | Cholestasis, liver disease | Knockout hepatocytes, bile flow assays |
| TAT-5 | Infertility | C. elegans knockout, sperm activation assays |
| ATP8A2 | Cerebellar degeneration | Knockout mice, motor function tests |
Cancer and Cell Proliferation
Glycerophospholipid flippases regulate endosomal phosphatidylserine, which is critical for the YAP signaling pathway in proliferating cells. Dysregulation of flippase activity can lead to uncontrolled cell proliferation, a hallmark of cancer. Targeting flippases may offer therapeutic strategies for cancers dependent on YAP signaling.
Thrombosis and Blood Coagulation
Loss of flippase activity results in phosphatidylserine exposure on platelets, promoting procoagulant activity and thrombin generation. Maintaining flippase activity in procoagulant platelets is a novel approach to reducing thrombin generation, suggesting that flippase modulators could be antithrombotic agents.
Apoptosis and Clearance of Apoptotic Cells
Phosphatidylserine exposure on the outer leaflet of apoptotic cells is a key signal for macrophage recognition and clearance. Flippase inactivation contributes to phosphatidylserine exposure during apoptosis. Defects in this process can lead to autoimmune diseases due to impaired clearance of apoptotic cells.
Fertilization and Infertility
Sperm activation for fertilization requires robust activity of the TAT-5 lipid flippase in C. elegans. This suggests that flippase activity is essential for male fertility, and its dysfunction may contribute to infertility.
From glycerophospholipid flippase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of ATP11A affect platelet procoagulant activity? | Knockout cell line (e.g., HEK293) or primary platelets |
| Does ATP11B point mutation alter YAP signaling? | Point mutation knock-in cell line |
| Does overexpression of ATP8A1 restore membrane asymmetry? | Overexpression cell line |
| Does tagged ATP11C localize to the plasma membrane? | Tagged knock-in cell line |
| Does TAT-5 knockout affect sperm activation? | C. elegans knockout |
| Does CDC50A knockout disrupt flippase maturation? | Knockout cell line |
How to Study the glycerophospholipid flippase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NBD-lipid flipping assay | Flippase activity | Real-time monitoring in live cells |
| ATPase activity assay | ATP hydrolysis | Enzymatic activity of P4-ATPases |
| Annexin V staining | Phosphatidylserine exposure | Apoptosis and platelet activation [1,6] |
| CRISPR knockout | Gene function | Causal link to flippase activity |
| Western blot | Protein expression | Flippase and subunit levels |
| Immunofluorescence | Subcellular localization | Membrane distribution |
| Flow cytometry | Cell surface phosphatidylserine | Platelet procoagulant activity |
| Thrombin generation assay | Coagulation potential | Thrombosis research |
Fluorescence-Based Flippase Assays
Flippase activity can be measured using fluorescently labeled phospholipid analogs, such as NBD-labeled phosphatidylserine, which are incorporated into the exoplasmic leaflet and their translocation to the cytosolic leaflet is monitored by fluorescence quenching or flow cytometry. This method allows real-time assessment of flippase activity in live cells.
ATPase Activity Assays
ATP hydrolysis by P4-ATPases can be measured using colorimetric or luminescent assays that detect inorganic phosphate release. This provides a direct measure of flippase catalytic activity and can be used to screen for inhibitors or activators.
Phosphatidylserine Exposure Detection
Annexin V staining followed by flow cytometry or microscopy is commonly used to detect phosphatidylserine exposure on the cell surface, which reflects loss of flippase activity [1,6]. This method is widely used in apoptosis and platelet studies [1,4].
Genetic Knockout and Rescue
CRISPR-Cas9 knockout of flippase genes followed by rescue with wild-type or mutant constructs can establish causality. This approach is essential for linking specific flippases to cellular phenotypes.
How CRISPR Can Be Used to Study GO:0140333 glycerophospholipid flippase activity
Knockout
CRISPR-Cas9 knockout of flippase genes such as ATP11A or ATP11B allows researchers to study loss-of-function phenotypes, including phosphatidylserine exposure and impaired signaling [2,5]. Knockout cell lines are valuable for validating the role of specific flippases in apoptosis, coagulation, and proliferation [1,4,5].
Point Mutation
Introducing point mutations in the catalytic domain of P4-ATPases, such as the aspartate residue involved in phosphorylation, can abolish flippase activity and help dissect the catalytic mechanism. Point mutation knock-in models are useful for studying disease-associated mutations.
Knock-in
Knock-in of tagged flippases (e.g., GFP or HA) enables visualization and immunoprecipitation of the protein to study localization and interactions. Knock-in of disease-relevant mutations can model human disorders.
Overexpression
Overexpression of wild-type or mutant flippases in cell lines can enhance flippase activity and rescue loss-of-function phenotypes. This approach is useful for structure-function studies and for screening modulators.
How EDITGENE Supports glycerophospholipid flippase activity Research
Researchers studying glycerophospholipid flippase activity-related genes often need to determine whether a candidate gene is causally involved in membrane lipid asymmetry, apoptosis, or coagulation. EDITGENE provides comprehensive CRISPR-based services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for glycerophospholipid flippase activity research.
Frequently Asked Questions About glycerophospholipid flippase activity
What is glycerophospholipid flippase activity?
Glycerophospholipid flippase activity (GO:0140333) is the ATP-dependent movement of glycerophospholipids from the exoplasmic to the cytosolic leaflet of a membrane.
What genes are involved in glycerophospholipid flippase activity?
Genes encoding P4-ATPases such as ATP8A1, ATP8A2, ATP8B1, ATP11A, ATP11B, ATP11C, and their accessory subunits CDC50A/B/C are involved.
What is the function of glycerophospholipid flippase activity?
It maintains asymmetric phospholipid distribution, regulates apoptosis, blood coagulation, and cell signaling [1,2,4,5].
Which diseases are associated with glycerophospholipid flippase activity?
Diseases include thrombosis, cancer, cholestasis, cerebellar degeneration, and infertility [2,4,5,7].
How is glycerophospholipid flippase activity regulated?
It is regulated by subunit association, phosphorylation, and membrane lipid composition.
What are the substrates of glycerophospholipid flippases?
Substrates include phosphatidylserine, phosphatidylethanolamine, and phosphatidylcholine.
What is the role of ATP11A in flippase activity?
ATP11A is a P4-ATPase that flips phosphatidylserine and is involved in apoptosis and coagulation [1,4].
How can I study glycerophospholipid flippase activity in the lab?
Use NBD-lipid flipping assays, ATPase activity assays, Annexin V staining, and CRISPR knockout models [2,4].
What is the relationship between flippase activity and apoptosis?
Loss of flippase activity leads to phosphatidylserine exposure, a signal for apoptotic cell clearance.
Does glycerophospholipid flippase activity require ATP?
Yes, it uses energy from ATP hydrolysis to transport lipids against the concentration gradient.
Conclusion
Glycerophospholipid flippase activity (GO:0140333) is a critical molecular function that maintains membrane lipid asymmetry and regulates diverse cellular processes including apoptosis, coagulation, and signaling. Dysregulation of this activity is linked to thrombosis, cancer, and infertility [4,5,7]. Understanding the mechanisms and regulation of flippases offers opportunities for therapeutic intervention. EDITGENE provides advanced CRISPR services to study these genes and accelerate discoveries.
References
- 1. Nagata S. 2018. Apoptosis and Clearance of Apoptotic Cells.. Annu Rev Immunol 36:489-517 PMID: 29400998
- 2. Sakuragi T et al.. 2023. Regulation of phospholipid distribution in the lipid bilayer by flippases and scramblases.. Nat Rev Mol Cell Biol 24(8):576-596 PMID: 37106071
- 3. Muranaka Y et al.. 2024. Novel phosphatidylinositol flippases contribute to phosphoinositide homeostasis in the plasma membrane.. Biochem J 481(18):1187-1202 PMID: 39258799
- 4. Millington-Burgess SL et al.. 2022. Maintaining flippase activity in procoagulant platelets is a novel approach to reducing thrombin generation.. J Thromb Haemost 20(4):989-995 PMID: 35034417
- 5. Matsudaira T et al.. 2017. Endosomal phosphatidylserine is critical for the YAP signalling pathway in proliferating cells.. Nat Commun 8(1):1246 PMID: 29093443
- 6. Shin HW et al.. 2020. Phosphatidylserine exposure in living cells.. Crit Rev Biochem Mol Biol 55(2):166-178 PMID: 32408772
- 7. Maniates KA et al.. 2025. Sperm activation for fertilization requires robust activity of the TAT-5 lipid flippase.. Dev Biol 528:66-78 PMID: 40915529
- 8. Sawasato K et al.. 2025. Its own architect: Flipping cardiolipin synthase.. Sci Adv 11(1):eads0244 PMID: 39752486
