GO:0140343 phosphatidylserine transfer activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0140343 phosphatidylserine transfer activity is a molecular_function that removes phosphatidylserine (PS) from the outer leaflet of a donor membrane, transports it through the aqueous phase protected in a hydrophobic pocket, and delivers it to the outer leaflet of an acceptor membrane.
• This activity is distinct from flippases, floppases and scramblases because it moves PS between membranes rather than across the two leaflets of a single bilayer.
• Proteins such as TMEM16F, TMEM16E, TMEM16A, and LYVAC/PDZD8 have been linked to phosphatidylserine handling and membrane lipid transfer in processes including blood coagulation, lysosomal repair, and endothelial procoagulant activity [4,6,7,1,2].
• Phosphatidylserine exposure and transfer are central to apoptosis and apoptotic cell clearance, where PS on the outer leaflet serves as an eat-me signal.
• Endosomal phosphatidylserine is required for YAP signalling in proliferating cells, linking PS distribution to growth-control pathways.
• CRISPR knockout, point-mutation, knock-in, and overexpression models enable causal testing of candidate PS transfer proteins in coagulation, lysosomal biology, and cell-signalling research.
Description
Phosphatidylserine (PS) is an anionic phospholipid that is normally enriched on the inner leaflet of the plasma membrane, but its exposure on the outer leaflet is a tightly controlled event in apoptosis, platelet activation, and membrane repair [3,6]. The Gene Ontology term GO:0140343, phosphatidylserine transfer activity, describes a molecular function in which PS is removed from the outer leaflet of a donor membrane, carried through the aqueous phase while shielded in a hydrophobic pocket, and delivered to the outer leaflet of an acceptor membrane. This activity is conceptually distinct from lipid scramblases, flippases, and floppases, which move lipids between leaflets of the same bilayer rather than between separate membranes. Researchers study phosphatidylserine transfer activity because PS distribution controls blood coagulation, apoptotic cell clearance, lysosomal membrane repair, and growth-factor signalling [3,6,1,8]. Defects in PS handling have been implicated in hereditary xerocytosis, thrombosis, and lysosomal dysfunction, making this GO term relevant to haematology, cell death, and membrane trafficking [6,7,1,2].
phosphatidylserine transfer activity At A Glance
| GO ID | GO:0140343 |
|---|---|
| GO term | phosphatidylserine transfer activity |
| Ontology | molecular_function |
| Synonym | intermembrane phosphatidylserine carrier activity |
| Major function | Removes phosphatidylserine from the outer leaflet of a donor membrane, transports it through the aqueous phase in a hydrophobic pocket, and delivers it to the outer leaflet of an acceptor membrane. |
| Substrate | Phosphatidylserine (PS), an anionic glycerophospholipid |
| Directionality | Donor membrane outer leaflet to acceptor membrane outer leaflet |
| Distinct from | Flippases, floppases, and scramblases that move lipids within one bilayer |
| Representative proteins | TMEM16 family members, LYVAC/PDZD8, and other PS-handling proteins [4,6,7,1,2] |
| Disease relevance | Coagulation disorders, thrombosis, lysosomal dysfunction, and apoptotic cell clearance defects [3,6,7,1,2] |
What Is GO:0140343?
GO:0140343 phosphatidylserine transfer activity is defined as the removal of phosphatidylserine from the outer leaflet of a donor membrane, its transport through the aqueous phase while protected in a hydrophobic pocket, and its delivery to the outer leaflet of an acceptor membrane. The synonym intermembrane phosphatidylserine carrier activity emphasizes that the substrate is carried between membranes rather than flipped across a single bilayer. This function requires a protein or protein complex with a hydrophobic cavity that can shield the PS headgroup and acyl chains from water during transit. The activity is therefore mechanistically distinct from ATP-dependent flippases, ABC transporters, and calcium-activated scramblases, although these systems can cooperate to establish the PS gradients that transfer proteins subsequently read out [3,6].
Why Is phosphatidylserine transfer activity Important in Cell Biology?
Phosphatidylserine transfer activity matters because PS is not merely a structural lipid; its exposure on the outer leaflet is a signal for blood coagulation, apoptotic cell recognition, and membrane repair [3,6]. The transfer of PS between membranes therefore sits at the intersection of haemostasis, cell death, and organelle quality control. For example, TMEM16F and TMEM16E have been linked to phosphatidylserine exposure and procoagulant activity in red blood cells and endothelial cells, and mutations in these proteins cause hereditary xerocytosis and bleeding phenotypes [6,7]. Lysosomal membrane repair requires rapid lipid redistribution, and LYVAC/PDZD8 has been identified as a lysosomal vacuolator involved in this process [1,2]. In proliferating cells, endosomal phosphatidylserine is critical for YAP signalling, connecting PS transfer to growth control. Understanding GO:0140343 thus provides mechanistic insight into diseases ranging from anaemia and thrombosis to neurodegeneration and cancer.
• PS exposure on the outer leaflet is an eat-me signal for apoptotic cell clearance by macrophages.
• TMEM16F is a calcium-activated phospholipid scramblase linked to PS exposure and hereditary xerocytosis.
• TMEM16E regulates endothelial cell procoagulant activity and thrombosis, implicating PS transfer in haemostasis.
• Lysosomal membrane repair requires rapid lipid redistribution, and LYVAC/PDZD8 functions as a lysosomal vacuolator [1,2].
• Endosomal phosphatidylserine is critical for YAP signalling in proliferating cells, linking PS to growth control.
• Anoctamin pharmacology is an active area because TMEM16 family members are drug targets.
• Mitochondrial bioenergetics stimulates autophagy for pathological MAPT/Tau clearance in tauopathy neurons, a process sensitive to membrane lipid status.
• PS transfer activity is distinct from scramblase activity, so specific assays are needed to assign function.
• CRISPR models allow causal testing of candidate PS transfer proteins in coagulation and lysosomal biology.
• Dysregulated PS exposure contributes to thrombosis and inflammatory clearance defects [3,6,7].
What Happens During phosphatidylserine transfer activity?
Donor membrane recognition and PS extraction
In simple terms: The transfer protein first finds a membrane that has phosphatidylserine on its outer surface and pulls one PS molecule out.
The first step of GO:0140343 is recognition of a donor membrane whose outer leaflet contains phosphatidylserine. This PS may have been exposed by a calcium-activated scramblase such as TMEM16F during platelet activation or apoptosis [3,6]. The transfer protein must then extract the PS molecule from the lipid bilayer, overcoming hydrophobic interactions with neighbouring lipids. This step is thought to require a hydrophobic pocket or groove that can accommodate the PS acyl chains. TMEM16 family proteins have been proposed to participate in phospholipid handling, and their pharmacology is under active investigation. The extraction step is distinct from scramblase activity because the PS leaves the donor membrane entirely rather than moving to the inner leaflet of the same bilayer.
Aqueous-phase transport in a hydrophobic pocket
In simple terms: The PS molecule is carried through the water-filled space between membranes inside a greasy pocket so it does not get damaged or lost.
Once extracted, PS must traverse the aqueous phase between the donor and acceptor membranes. Because PS is amphipathic and poorly soluble in water, the transfer protein shields it in a hydrophobic pocket or channel. This is the defining feature of intermembrane phosphatidylserine carrier activity. The transport step is energy-independent in the sense that it does not require ATP hydrolysis for the transfer itself, although the PS gradient across membranes is maintained by other systems. LYVAC/PDZD8 has been identified as a lysosomal vacuolator, and its function may involve lipid transfer at lysosomal membranes [1,2]. The aqueous-phase transport step ensures that PS is not exposed to the cytosol, which would otherwise trigger inappropriate signalling or aggregation.
Acceptor membrane delivery and PS insertion
In simple terms: The carrier releases the PS into the outer leaflet of the target membrane.
The final step of GO:0140343 is delivery of PS to the outer leaflet of an acceptor membrane. This step may be coupled to membrane contact sites, where two organelles are held in close apposition. Endosomal phosphatidylserine is critical for YAP signalling in proliferating cells, suggesting that PS delivery to endosomal membranes has signalling consequences. In apoptotic cells, PS exposed on the outer leaflet serves as an eat-me signal for phagocytes, and the transfer machinery must cooperate with scramblases to maintain this exposure. TMEM16E regulates endothelial cell procoagulant activity and thrombosis, and its function likely involves PS delivery to the endothelial surface. The acceptor membrane may be the plasma membrane, an endosome, a lysosome, or another organelle, depending on the biological context.
Coupling to membrane repair and lysosomal homeostasis
In simple terms: PS transfer helps patch damaged membranes and keep lysosomes healthy.
Phosphatidylserine transfer activity is functionally coupled to membrane repair and lysosomal homeostasis. A phosphoinositide signalling pathway mediates rapid lysosomal repair, and lipid transfer events are likely part of this response. LYVAC/PDZD8 is a lysosomal vacuolator, and its activity may influence lysosomal membrane dynamics. Mitochondrial bioenergetics stimulates autophagy for pathological MAPT/Tau clearance in tauopathy neurons, a process that depends on membrane lipid status. These observations suggest that PS transfer activity is not an isolated event but is integrated with organelle quality control and autophagy. Defects in this coupling could contribute to lysosomal storage disorders and neurodegeneration.
Regulation by calcium and phosphoinositides
In simple terms: Calcium and phosphoinositide signals tell the transfer machinery when and where to act.
Calcium signalling is a major regulator of PS exposure and transfer. TMEM16F is a calcium-activated phospholipid scramblase, and its activity is required for PS exposure in platelets and red blood cells. TMEM16E also regulates procoagulant activity in endothelial cells, and anoctamin pharmacology is an active field because these proteins are drug targets [4,7]. Phosphoinositides mediate rapid lysosomal repair, and phosphoinositide signalling may recruit lipid transfer proteins to damaged membranes. Endosomal phosphatidylserine is critical for YAP signalling, indicating that PS distribution is read by growth-control pathways. Together, calcium and phosphoinositide signals provide spatial and temporal control of phosphatidylserine transfer activity.
Key Genes Involved in GO:0140343 phosphatidylserine transfer activity
The following genes and proteins have been linked to phosphatidylserine handling, membrane lipid transfer, or related processes in the verified literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| TMEM16F (ANO6) | Calcium-activated phospholipid scramblase involved in PS exposure | Hereditary xerocytosis; platelet procoagulant activity |
| TMEM16E (ANO5) | Regulates endothelial cell procoagulant activity | Thrombosis; bleeding disorders |
| TMEM16A (ANO1) | Anoctamin family member with phospholipid handling roles | Anoctamin pharmacology; ion transport |
| LYVAC/PDZD8 | Lysosomal vacuolator involved in lipid transfer | Lysosomal membrane repair; organelle homeostasis |
| PIEZO1 | Mechanosensitive channel linked to TMEM16F interplay | Hereditary xerocytosis; red cell dehydration |
| YAP | Transcriptional regulator downstream of endosomal PS | Proliferative signalling; organ size control |
| MAPT/Tau | Microtubule-associated protein cleared by autophagy | Tauopathy; neurodegeneration |
| VPS34/PIK3C3 | Phosphoinositide kinase involved in lysosomal repair | Lysosomal repair signalling |
| PI4K2A | Phosphoinositide kinase implicated in lysosomal repair | Membrane repair; phosphoinositide signalling |
| ATG proteins | Autophagy machinery stimulated by mitochondrial bioenergetics | Tau clearance; autophagy regulation |
| Phagocyte receptors | Recognize PS on apoptotic cells | Apoptotic cell clearance; immunology |
| Caspases | Executioner proteases in apoptosis | Apoptosis; PS exposure |
| Calcium channels | Provide calcium signals for scramblase activation | Coagulation; platelet biology |
| Endosomal trafficking proteins | Control PS distribution to endosomes | YAP signalling; proliferation |
| Lysosomal membrane proteins | Maintain lysosomal integrity | Lysosomal repair; storage disorders [1,2] |
| Anoctamin modulators | Pharmacological tools targeting TMEM16 proteins | Drug discovery; anoctamin pharmacology |
How Is phosphatidylserine transfer activity Regulated?
Phosphatidylserine transfer activity is regulated by calcium signalling, phosphoinositide metabolism, and membrane contact site formation. Calcium-activated scramblases such as TMEM16F expose PS on the outer leaflet, providing substrate for transfer proteins. Phosphoinositide signalling mediates rapid lysosomal repair, and phosphoinositide kinases such as VPS34/PIK3C3 and PI4K2A are involved in this response. Endosomal phosphatidylserine is critical for YAP signalling, indicating that PS distribution is coupled to growth-control pathways. Mitochondrial bioenergetics stimulates autophagy for pathological MAPT/Tau clearance, linking metabolic state to membrane lipid dynamics. Anoctamin pharmacology is an active area because TMEM16 family members are drug targets, and their modulation could affect PS transfer indirectly.
phosphatidylserine transfer activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| TMEM16F (ANO6) | Hereditary xerocytosis; platelet procoagulant activity | Knockout and point-mutation iPSC-derived megakaryocytes |
| TMEM16E (ANO5) | Thrombosis; endothelial procoagulant activity | Endothelial cell knockout and overexpression models |
| PIEZO1 | Hereditary xerocytosis; red cell dehydration | Knock-in mouse models and red cell assays |
| LYVAC/PDZD8 | Lysosomal vacuolation; membrane repair | Knockout HeLa cells and lysosomal repair assays |
| MAPT/Tau | Tauopathy; neurodegeneration | Patient iPSC-derived neurons and autophagy assays |
Hereditary xerocytosis and red blood cell disorders
Hereditary xerocytosis is caused by mutations in PIEZO1 and is characterized by red blood cell dehydration and altered PS exposure. TMEM16F interacts with PIEZO1, and disrupting this interplay affects red cell biology. TMEM16F is a calcium-activated phospholipid scramblase, and its dysfunction leads to defective PS exposure and coagulation abnormalities. These findings link phosphatidylserine transfer activity to anaemia and thrombotic risk.
Thrombosis and endothelial procoagulant activity
TMEM16E regulates endothelial cell procoagulant activity and thrombosis, and its loss or mutation may alter PS exposure on endothelial surfaces. Anoctamin pharmacology is relevant because TMEM16 family members are potential drug targets for thrombotic disorders. PS exposure on activated platelets and endothelial cells is a key step in coagulation, making PS transfer activity a therapeutic target [6,7].
Lysosomal dysfunction and neurodegeneration
A phosphoinositide signalling pathway mediates rapid lysosomal repair, and lipid transfer events are part of this response. LYVAC/PDZD8 is a lysosomal vacuolator, and its dysfunction may impair lysosomal membrane homeostasis. Mitochondrial bioenergetics stimulates autophagy for pathological MAPT/Tau clearance in tauopathy neurons, and membrane lipid status influences this process. These findings connect phosphatidylserine transfer activity to lysosomal storage disorders and neurodegeneration.
Apoptosis and apoptotic cell clearance
PS exposure on the outer leaflet of apoptotic cells is an eat-me signal for phagocytes, and defects in this process lead to autoimmunity and inflammation. Phosphatidylserine transfer activity may contribute to the redistribution of PS during apoptosis, although the exact molecular players remain to be fully defined. Understanding this pathway could inform therapies for inflammatory and autoimmune diseases.
From phosphatidylserine transfer activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of TMEM16F alter PS exposure and coagulation? | TMEM16F knockout cell line and platelet function assays |
| Does TMEM16E mutation affect endothelial procoagulant activity? | TMEM16E point-mutation knock-in endothelial cells |
| Does LYVAC/PDZD8 regulate lysosomal membrane repair? | LYVAC/PDZD8 knockout cells with lysosomal damage assays |
| Does endosomal PS control YAP signalling? | PS transfer protein knockout with YAP reporter assays |
| Does PS transfer activity influence Tau clearance? | Tauopathy neuron models with autophagy flux assays |
| Can anoctamin modulators alter PS transfer? | Pharmacological screens in TMEM16-expressing cells |
How to Study the phosphatidylserine transfer activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Fluorescent PS transfer assay | Transfer of PS between liposomes | Testing candidate transfer proteins [2,4] |
| Annexin V flow cytometry | PS exposure on outer leaflet | Platelet and red cell activation [6,7] |
| Lysosomal dextran release | Lysosomal membrane integrity | Lysosomal repair studies [1,2] |
| YAP luciferase reporter | YAP transcriptional activity | Endosomal PS signalling |
| LC3B/p62 immunoblot | Autophagy flux | Tau clearance in neurons |
| Phagocytosis assay | Clearance of apoptotic cells | Apoptotic cell recognition |
| Calcium imaging | Intracellular calcium signals | Scramblase activation |
| Anoctamin pharmacology | Modulation of TMEM16 activity | Drug discovery |
Lipid transfer assays
In vitro lipid transfer assays using fluorescent PS analogues and donor/acceptor liposomes can directly measure phosphatidylserine transfer activity. These assays are used to test candidate proteins such as TMEM16 family members and LYVAC/PDZD8 [2,4]. They can be coupled to calcium and phosphoinositide modulators to study regulation [1,6].
PS exposure and scramblase assays
Annexin V binding and flow cytometry are standard methods to measure PS exposure on the outer leaflet of cells. These assays are used to study TMEM16F and TMEM16E function in platelets, red blood cells, and endothelial cells [6,7]. Calcium ionophores and anoctamin modulators can be used to activate or inhibit scramblase activity.
Lysosomal repair and imaging
Lysosomal membrane repair can be monitored using fluorescent dextran release assays and live-cell imaging. LYVAC/PDZD8 knockout cells show lysosomal vacuolation, which can be quantified by electron microscopy or fluorescent markers. Phosphoinositide signalling during lysosomal repair can be studied with genetically encoded biosensors.
Signalling and autophagy readouts
YAP signalling can be measured by luciferase reporters and immunofluorescence for YAP nuclear localization in cells with altered endosomal PS. Autophagy flux can be assessed by LC3B and p62 immunoblotting in tauopathy neuron models. Apoptotic cell clearance can be studied using co-culture assays with phagocytes and PS-coated targets.
How CRISPR Can Be Used to Study GO:0140343 phosphatidylserine transfer activity
Knockout
CRISPR knockout of candidate PS transfer genes such as TMEM16F, TMEM16E, or LYVAC/PDZD8 can reveal loss-of-function phenotypes in PS exposure, coagulation, and lysosomal repair [6,7,2]. Knockout cell lines are useful for validating antibody specificity and for rescue experiments. For example, TMEM16F knockout cells show defective PS exposure and can be rescued by wild-type but not mutant TMEM16F.
Point Mutation
Point mutations identified in patients with hereditary xerocytosis or bleeding disorders can be introduced into endogenous genes using CRISPR prime editing or homology-directed repair. These models help distinguish pathogenic variants from benign polymorphisms [6,7]. For example, disease-associated TMEM16F mutations can be tested for their effect on PS scrambling and coagulation.
Knock-in
Knock-in of fluorescent or epitope tags into endogenous PS transfer genes allows live-cell imaging and proteomic analysis. Tagged LYVAC/PDZD8 or TMEM16E can be used to track localization to lysosomes or the plasma membrane [2,7]. Knock-in of reporter cassettes can also be used to monitor gene expression in response to calcium or phosphoinositide signals.
Overexpression
Overexpression of wild-type or mutant PS transfer proteins can be used to test gain-of-function effects on PS distribution and downstream signalling. Overexpression of TMEM16E in endothelial cells can increase procoagulant activity, while overexpression of LYVAC/PDZD8 may alter lysosomal morphology [7,2]. Overexpression models are also useful for structural and biochemical studies of the transfer mechanism.
How EDITGENE Supports phosphatidylserine transfer activity Research
Researchers studying phosphatidylserine transfer activity-related genes often need to determine whether a candidate gene is causally involved in PS distribution, membrane repair, or coagulation. EDITGENE provides CRISPR-based cell model services that enable precise genetic manipulation of TMEM16 family members, LYVAC/PDZD8, and other PS-handling genes.
Contact EDITGENE today to design your custom CRISPR model for phosphatidylserine transfer activity research.
Frequently Asked Questions About phosphatidylserine transfer activity
What is phosphatidylserine transfer activity?
Phosphatidylserine transfer activity (GO:0140343) is a molecular function that removes phosphatidylserine from the outer leaflet of a donor membrane, transports it through the aqueous phase in a hydrophobic pocket, and delivers it to the outer leaflet of an acceptor membrane.
What genes are involved in phosphatidylserine transfer activity?
Genes linked to PS handling include TMEM16F, TMEM16E, TMEM16A, LYVAC/PDZD8, and PIEZO1, based on studies of PS exposure, coagulation, and lysosomal repair [4,6,7,1,2].
How is phosphatidylserine transfer activity different from scramblase activity?
Scramblases move lipids between the two leaflets of the same membrane, whereas phosphatidylserine transfer activity moves PS between separate donor and acceptor membranes.
Why is phosphatidylserine exposure important in apoptosis?
PS exposure on the outer leaflet of apoptotic cells serves as an eat-me signal for phagocytes, enabling clearance of dying cells.
What diseases are linked to phosphatidylserine transfer activity?
Diseases include hereditary xerocytosis, thrombosis, lysosomal dysfunction, and neurodegenerative conditions such as tauopathy [6,7,1,2,5].
How can I study phosphatidylserine transfer activity in the lab?
Common methods include fluorescent PS transfer assays, Annexin V flow cytometry, lysosomal repair imaging, YAP reporter assays, and autophagy flux measurements [2,6,1,8,5].
What is the role of TMEM16F in phosphatidylserine exposure?
TMEM16F is a calcium-activated phospholipid scramblase that exposes PS on the outer leaflet and is linked to hereditary xerocytosis and platelet procoagulant activity.
Does LYVAC/PDZD8 regulate lysosomal membranes?
LYVAC/PDZD8 has been identified as a lysosomal vacuolator, and its function may involve lipid transfer at lysosomal membranes.
Can CRISPR be used to study phosphatidylserine transfer genes?
Yes, CRISPR knockout, point-mutation, knock-in, and overexpression models enable causal testing of candidate PS transfer genes in coagulation, lysosomal biology, and signalling [6,7,2,8].
What is the GO ID for phosphatidylserine transfer activity?
The GO ID is GO:0140343, with the synonym intermembrane phosphatidylserine carrier activity.
Conclusion
GO:0140343 phosphatidylserine transfer activity defines a molecular function that moves PS between membranes, distinct from scramblases and flippases. This activity is central to apoptosis, coagulation, lysosomal repair, and growth signalling, with TMEM16 family members and LYVAC/PDZD8 as key players [3,6,7,1,2,8]. CRISPR-based cell models provide a powerful approach to dissect the causal roles of these proteins in health and disease.
References
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- 2. Yang H et al.. 2025. LYVAC/PDZD8 is a lysosomal vacuolator.. Science 389(6762):eadz0972 PMID: 40839735
- 3. Nagata S. 2018. Apoptosis and Clearance of Apoptotic Cells.. Annu Rev Immunol 36:489-517 PMID: 29400998
- 4. Genovese M et al.. 2024. Anoctamin pharmacology.. Cell Calcium 121:102905 PMID: 38788257
- 5. Jia N et al.. 2025. Mitochondrial bioenergetics stimulates autophagy for pathological MAPT/Tau clearance in tauopathy neurons.. Autophagy 21(1):54-79 PMID: 39171695
- 6. Liang P et al.. 2024. Deciphering and disrupting PIEZO1-TMEM16F interplay in hereditary xerocytosis.. Blood 143(4):357-369 PMID: 38033286
- 7. Schmaier AA et al.. 2023. TMEM16E regulates endothelial cell procoagulant activity and thrombosis.. J Clin Invest 133(11) PMID: 36951953
- 8. Matsudaira T et al.. 2017. Endosomal phosphatidylserine is critical for the YAP signalling pathway in proliferating cells.. Nat Commun 8(1):1246 PMID: 29093443
