GO:0120013 lipid transfer activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0120013 lipid transfer activity describes the removal of a lipid from a membrane or monolayer lipid particle, its transport through the aqueous phase protected in a hydrophobic pocket, and its delivery to an acceptor membrane or lipid particle.
• This activity enables intermembrane lipid transfer and is distinct from lipid synthesis, hydrolysis, or simple diffusion.
• Key proteins with lipid transfer activity include CETP, PLTP, ATG2B, and members of the lipid transfer protein family such as ORP and CERT proteins.
• Elevated CETP lipid transfer activity is associated with increased risk of venous thromboembolism, linking this molecular function to human disease.
• ATG2B lipid transfer activity is accelerated by negatively charged lipids and WIPI4, connecting it to autophagosome formation.
• Studying lipid transfer activity requires assays that measure lipid movement between membranes or lipoprotein particles, often using fluorescence or radiolabeled lipids.
Description
Lipid transfer activity (GO:0120013) is a molecular function that moves lipids between membranes or lipid particles without chemically modifying them. This activity is essential for maintaining membrane lipid composition, lipoprotein metabolism, and cellular signaling. Proteins with this activity extract a lipid from a donor membrane, shield it from the aqueous environment within a hydrophobic pocket, and deposit it into an acceptor membrane. Dysregulation of lipid transfer activity contributes to diseases such as atherosclerosis and venous thromboembolism. Understanding the mechanisms, genes, and regulation of lipid transfer activity is therefore critical for both basic cell biology and therapeutic development.
lipid transfer activity At A Glance
| GO ID | GO:0120013 |
|---|---|
| GO term | lipid transfer activity |
| Ontology | molecular_function |
| Synonym | intermembrane lipid transfer activity; lipid carrier activity |
| Major function | Transfers lipids between membranes or lipid particles through an aqueous phase |
| Definition source | QuickGO |
| Related processes | Lipid transport, membrane biogenesis, lipoprotein metabolism, autophagy |
What Is GO:0120013?
GO:0120013 lipid transfer activity is defined as the process that removes a lipid from a membrane or a monolayer lipid particle, transports it through the aqueous phase while protected in a hydrophobic pocket, and brings it to an acceptor membrane or lipid particle, resulting in intermembrane transfer of lipids. This activity does not involve covalent modification of the lipid; it is a carrier-mediated transport function.
Why Is lipid transfer activity Important in Cell Biology?
Lipid transfer activity is fundamental to cellular lipid homeostasis and membrane dynamics. It enables the exchange of lipids between organelles and lipoproteins, influencing processes such as signal transduction, energy metabolism, and autophagy. Clinically, altered lipid transfer activity is linked to cardiovascular and metabolic disorders, including venous thromboembolism and atherosclerosis. Therefore, targeting lipid transfer proteins may offer therapeutic strategies for these conditions.
• Maintains membrane lipid asymmetry and composition.
• Regulates lipoprotein metabolism and reverse cholesterol transport.
• Facilitates autophagosome formation by transferring lipids to expanding phagophores.
• Modulates Wnt morphogen secretion and signaling via extracellular carriers.
• Influences energy metabolism through long-chain fatty acid handling.
• Associated with risk of venous thromboembolism when CETP activity is elevated.
• Contributes to coronary atherosclerotic plaque regression when lipid transfer is modulated.
• Involved in lipid droplet dynamics and cellular lipid storage.
• Potential target for exercise-induced neurogenesis via blood factors.
• Provides a mechanism for inter-organelle communication independent of vesicular traffic.
What Happens During lipid transfer activity?
Lipid extraction from donor membrane
In simple terms: The transfer protein grabs a lipid molecule from one membrane.
The lipid transfer protein binds to a donor membrane or lipid particle and extracts a specific lipid molecule. This step often requires a hydrophobic pocket to accommodate the lipid's acyl chains. The extraction is driven by lipid concentration gradients and membrane curvature.
Aqueous phase transport
In simple terms: The protein carries the lipid through water, hiding it from water.
After extraction, the lipid is shielded within a hydrophobic tunnel or pocket of the transfer protein, allowing it to traverse the aqueous cytoplasm or extracellular space without aggregating or being modified. This protection is essential for efficient transfer.
Delivery to acceptor membrane
In simple terms: The protein releases the lipid into a second membrane.
The transfer protein docks onto an acceptor membrane or lipid particle and releases the lipid. This step may be facilitated by membrane contact sites or specific lipid composition. The directionality of transfer depends on lipid gradients and protein conformation.
Regulation by accessory proteins and lipids
In simple terms: Other molecules can speed up or slow down the transfer.
Accessory proteins such as WIPI4 and negatively charged lipids accelerate ATG2B-mediated lipid transfer. Conversely, lipid transfer inhibitor protein (LTIP) can modulate CETP activity in plasma. These regulatory interactions fine-tune lipid transfer in response to cellular needs.
Key Genes Involved in GO:0120013 lipid transfer activity
The following genes encode proteins with demonstrated or putative lipid transfer activity, as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CETP | Transfers cholesteryl esters and triglycerides between lipoproteins | Elevated activity linked to venous thromboembolism risk |
| PLTP | Transfers phospholipids between lipoproteins | Involved in HDL remodeling and atherosclerosis |
| ATG2B | Transfers lipids to expanding phagophores during autophagy | Accelerated by WIPI4 and negatively charged lipids |
| CERT | Transfers ceramide from ER to Golgi | Sphingolipid homeostasis and signaling |
| ORP family | Transfers sterols and phospholipids at membrane contact sites | Cholesterol trafficking and organelle communication |
| NPC1 | Transfers cholesterol out of lysosomes | Niemann-Pick disease and lipid storage |
| ABCA1 | Transfers phospholipids and cholesterol to apoA-I | HDL biogenesis and reverse cholesterol transport |
| SR-BI | Facilitates selective cholesteryl ester uptake | Lipoprotein metabolism and atherosclerosis |
| LTP | Lipid transfer protein in plants | Plant defense and membrane remodeling |
| LTIP | Inhibits CETP-mediated lipid transfer | Regulates plasma lipid transfer activity |
| WIPI4 | Enhances ATG2B lipid transfer activity | Autophagy regulation |
| VPS13 | Transfers lipids at membrane contact sites | Neurodegeneration and lipid homeostasis |
| C2CD2L | Lipid transfer at ER-plasma membrane junctions | Calcium and lipid signaling |
| TTPA | Transfers alpha-tocopherol between membranes | Vitamin E metabolism and ataxia |
| CETP-like proteins | Lipid transfer in invertebrates | Comparative lipid biology |
| GLTP | Transfers glycolipids between membranes | Glycolipid metabolism and cancer |
How Is lipid transfer activity Regulated?
Lipid transfer activity is regulated at multiple levels. Accessory proteins such as WIPI4 enhance ATG2B-mediated transfer, while negatively charged lipids accelerate the process. Lipid transfer inhibitor protein (LTIP) specifically inhibits CETP activity in human plasma, providing a feedback mechanism. Additionally, long-chain fatty acids can regulate energy metabolism and potentially influence lipid transfer protein expression. Hormonal and metabolic signals, such as those induced by exercise, may also modulate lipid transfer activity through blood factors.
lipid transfer activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CETP | Venous thromboembolism | CETP knockout or point-mutation cell lines |
| ATG2B | Autophagy-related disorders | ATG2B knockout HeLa cells |
| ABCA1 | Tangier disease | ABCA1 knockout macrophages |
| NPC1 | Niemann-Pick disease type C | NPC1 mutant fibroblasts |
| VPS13 | Neurodegeneration | VPS13 knockdown neurons |
Cardiovascular disease
Elevated CETP lipid transfer activity is associated with an increased risk of venous thromboembolism. Modulating lipid transfer activity can influence coronary atherosclerotic plaque regression, suggesting a therapeutic avenue for cardiovascular disease.
Metabolic disorders
Lipid transfer proteins are integral to lipoprotein metabolism and energy homeostasis. Dysregulation of long-chain fatty acid handling contributes to metabolic syndrome and diabetes. Lipid droplet metabolism, which involves lipid transfer, is also implicated in obesity and insulin resistance.
Neurodegeneration
Blood factors that transfer beneficial effects of exercise on neurogenesis and cognition may involve lipid transfer activity. Additionally, proteins like VPS13, which mediate lipid transfer at membrane contact sites, are linked to neurodegenerative disorders.
Cancer
Extracellular carriers control lipid-dependent secretion and activity of WNT morphogens, which are critical in cancer signaling. Glycolipid transfer proteins such as GLTP are implicated in cancer cell proliferation and survival.
From lipid transfer activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does CETP lipid transfer activity directly cause venous thromboembolism? | CETP knockout or point-mutation cell lines |
| How does ATG2B lipid transfer activity affect autophagosome formation? | ATG2B knockout HeLa cells |
| What is the role of ABCA1 in HDL biogenesis? | ABCA1 knockout macrophages |
| Does WIPI4 enhance ATG2B-mediated lipid transfer? | WIPI4 overexpression or knockout cells |
| How does LTIP regulate CETP activity? | LTIP overexpression in plasma |
| Can modulating lipid transfer activity regress atherosclerotic plaques? | ApoE knockout mice with CETP overexpression |
How to Study the lipid transfer activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Fluorescence lipid transfer assay | Real-time lipid transfer between membranes | High-throughput screening of inhibitors |
| Radiolabeled lipid transfer assay | Quantitative lipid transfer activity | Plasma LTIP activity measurement |
| Lipidomics (LC-MS) | Lipid species composition | Membrane remodeling studies |
| CRISPR knockout screen | Genes required for lipid transfer | Identification of novel lipid transfer proteins |
| Live-cell imaging | Lipid transfer at membrane contact sites | Organelle dynamics |
| Proteomics | Protein interactions with lipid transfer proteins | Complex composition |
| Autophagosome formation assay | ATG2B-mediated lipid transfer | Autophagy regulation |
| Lipoprotein profiling | CETP-mediated lipid exchange | Cardiovascular risk assessment |
Fluorescence-based lipid transfer assays
These assays use fluorescently labeled lipids to monitor transfer between donor and acceptor membranes or lipoproteins. They provide real-time kinetic data and are suitable for high-throughput screening.
Radiolabeled lipid transfer assays
Radiolabeled lipids are used to quantify transfer activity in plasma or cell lysates. This method is highly sensitive and can measure endogenous lipid transfer inhibitor protein activity.
Lipidomics and mass spectrometry
Mass spectrometry-based lipidomics can quantify changes in lipid composition across membranes or organelles after modulating lipid transfer proteins. This approach provides a comprehensive view of lipid species affected.
CRISPR screening and knockout models
Genome-wide CRISPR knockout screens can identify genes required for lipid transfer activity. Knockout cell lines for candidate genes such as CETP or ATG2B allow functional validation.
How CRISPR Can Be Used to Study GO:0120013 lipid transfer activity
Knockout
CRISPR knockout of genes encoding lipid transfer proteins, such as CETP or ATG2B, allows researchers to assess loss-of-function phenotypes. For example, ATG2B knockout cells exhibit defective autophagosome formation, confirming its role in lipid transfer.
Point Mutation
Introducing point mutations in catalytic or lipid-binding residues of lipid transfer proteins can dissect their mechanism. For instance, mutating the hydrophobic pocket of CETP can abolish lipid transfer activity without affecting protein stability.
Knock-in
Knock-in of tagged versions of lipid transfer proteins (e.g., GFP-ATG2B) enables live-cell imaging and proteomic analysis. This approach helps track protein localization and interactions during lipid transfer.
Overexpression
Overexpression of lipid transfer proteins such as WIPI4 or CETP can amplify lipid transfer activity, facilitating biochemical assays and disease modeling. Overexpression in cell lines or animal models can reveal gain-of-function phenotypes.
How EDITGENE Supports lipid transfer activity Research
Researchers studying lipid transfer activity-related genes often need to determine whether a candidate gene is causally involved in lipid movement, membrane remodeling, or disease. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for lipid transfer activity research.
Frequently Asked Questions About lipid transfer activity
What is lipid transfer activity?
Lipid transfer activity (GO:0120013) is a molecular function that moves lipids between membranes or lipid particles through an aqueous phase, protected in a hydrophobic pocket.
What genes are involved in lipid transfer activity?
Key genes include CETP, PLTP, ATG2B, CERT, ORP family, NPC1, ABCA1, and GLTP, among others.
How is lipid transfer activity measured?
It is measured using fluorescence-based or radiolabeled lipid transfer assays, lipidomics, and CRISPR screens.
What diseases are associated with lipid transfer activity?
Diseases include venous thromboembolism, atherosclerosis, metabolic disorders, neurodegeneration, and cancer.
What is the role of CETP in lipid transfer?
CETP transfers cholesteryl esters and triglycerides between lipoproteins; elevated activity is linked to venous thromboembolism.
How does ATG2B mediate lipid transfer?
ATG2B transfers lipids to expanding phagophores during autophagy, and its activity is accelerated by WIPI4 and negatively charged lipids.
Can CRISPR be used to study lipid transfer activity?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models allow functional dissection of lipid transfer genes.
What is lipid transfer inhibitor protein?
LTIP is a plasma protein that inhibits CETP-mediated lipid transfer, regulating lipid transfer activity.
Which GO term describes lipid transfer activity?
The Gene Ontology term is GO:0120013, lipid transfer activity, under molecular_function.
Why is lipid transfer activity important for cell biology?
It maintains membrane lipid composition, enables lipoprotein metabolism, and supports autophagy and signaling.
Conclusion
Lipid transfer activity (GO:0120013) is a fundamental molecular function that moves lipids between membranes and particles, impacting cardiovascular health, metabolism, autophagy, and signaling. Key proteins such as CETP, ATG2B, and ABCA1 are central to this activity, and their dysregulation contributes to human diseases. CRISPR-based models and advanced assays provide powerful tools to dissect the mechanisms and therapeutic potential of lipid transfer activity.
References
- 1. Dawson LP et al.. 2022. Coronary Atherosclerotic Plaque Regression: JACC State-of-the-Art Review.. J Am Coll Cardiol 79(1):66-82 PMID: 34991791
- 2. Nakamura MT et al.. 2014. Regulation of energy metabolism by long-chain fatty acids.. Prog Lipid Res 53:124-44 PMID: 24362249
- 3. Horowitz AM et al.. 2020. Blood factors transfer beneficial effects of exercise on neurogenesis and cognition to the aged brain.. Science 369(6500):167-173 PMID: 32646997
- 4. de Almeida Magalhaes T et al.. 2024. Extracellular carriers control lipid-dependent secretion, delivery, and activity of WNT morphogens.. Dev Cell 59(2):244-261.e6 PMID: 38154460
- 5. Deguchi H et al.. 2016. Elevated CETP Lipid Transfer Activity is Associated with the Risk of Venous Thromboembolism.. J Atheroscler Thromb 23(10):1159-1167 PMID: 27169917
- 6. Khor VK et al.. 2013. Lipid droplet metabolism.. Curr Opin Clin Nutr Metab Care 16(6):632-7 PMID: 24100667
- 7. Osawa T et al.. 2020. Human ATG2B possesses a lipid transfer activity which is accelerated by negatively charged lipids and WIPI4.. Genes Cells 25(1):65-70 PMID: 31721365
- 8. Morton RE et al.. 1993. Determination of lipid transfer inhibitor protein activity in human lipoprotein-deficient plasma.. Arterioscler Thromb 13(12):1843-51 PMID: 8241106
