GO:0005041 low-density lipoprotein particle receptor activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0005041 (low-density lipoprotein particle receptor activity) is a molecular function defined as combining with a low-density lipoprotein particle and delivering it into the cell via endocytosis.
• The activity is best known for the LDLR protein, which mediates holoparticle uptake of LDL and is a central determinant of plasma cholesterol homeostasis.
• LDL receptor activity is not static: it is rapidly regulated by sterol availability and by extracellular cues in cultured human fibroblasts and arterial smooth muscle cells.
• Beyond cholesterol metabolism, LDL receptor activity is relevant to cancer biology, including intracranial tumors and endometrial cancer progression through LRP5/6 signaling.
• Dietary and pharmacological factors, such as n-3 fatty acids and quercetin, can modulate LDL receptor activity and related inflammatory pathways.
• CRISPR-based knockout, point-mutation, knock-in, and overexpression models enable causal dissection of GO:0005041 in disease-relevant cell types.
Description
GO:0005041, low-density lipoprotein particle receptor activity, is a molecular function that captures the ability of a cell-surface receptor to bind a low-density lipoprotein (LDL) particle and deliver it into the cell through endocytosis. This activity is a cornerstone of lipoprotein metabolism because it determines how efficiently cells clear LDL from the extracellular environment and how much cholesterol they internalize. The function is classically associated with the LDL receptor (LDLR), but the broader concept encompasses receptor-mediated uptake mechanisms that can be studied in many cell types. For researchers, GO:0005041 provides a precise annotation target when linking genotype to cellular lipid handling, membrane trafficking, and disease phenotypes. The physiological importance of this activity is underscored by its rapid regulation. In cultured human fibroblasts, LDL receptor activity is acutely adjusted in response to cholesterol status, demonstrating that the function is dynamically controlled rather than constitutively fixed. Similarly, cultured human arterial smooth muscle cells regulate LDL receptor activity, linking this molecular function to vascular biology and atherosclerosis research. Because atherogenic LDL particles are central to cardiovascular risk, understanding the receptors that mediate their uptake is directly relevant to disease prevention and therapy. In addition to cardiovascular contexts, low-density lipoprotein particle receptor activity has been studied in cancer. Human intracranial tumors show LDL receptor activity that relates to their cholesterol requirement, suggesting that proliferating tumor cells may depend on this uptake route. More recent work implicates LRP5/6, which are related to LDL receptor family signaling, in endometrial cancer progression and immune escape. These findings position GO:0005041 as a function that bridges lipid metabolism, cell signaling, and oncology.
low-density lipoprotein particle receptor activity At A Glance
| GO ID | GO:0005041 |
|---|---|
| GO term | low-density lipoprotein particle receptor activity |
| Ontology | molecular_function |
| Synonym | LDLR activity; LDL receptor; low-density lipoprotein receptor activity |
| Definition | Combining with a low-density lipoprotein particle and delivering the low-density lipoprotein particle into the cell via endocytosis |
| Major function | Receptor-mediated binding and endocytic uptake of LDL particles |
| Representative protein | LDLR (low-density lipoprotein receptor) |
| Related family members | LRP5, LRP6 and other LDL receptor-related proteins |
| Cellular context | Plasma membrane and endocytic trafficking compartments |
| Disease relevance | Atherosclerosis, cardiovascular risk, intracranial tumors, endometrial cancer |
What Is GO:0005041?
In simple terms, GO:0005041 describes what happens when a receptor on the cell surface grabs an LDL particle and pulls it inside the cell. The QuickGO definition states that this activity involves combining with a low-density lipoprotein particle and delivering the low-density lipoprotein particle into the cell via endocytosis. It is a molecular function, meaning it describes a specific activity performed by a gene product rather than a whole pathway or cellular structure. Synonyms include LDLR activity, LDL receptor, and low-density lipoprotein receptor activity, reflecting the historical and current naming of the proteins that carry out this function.
Why Is low-density lipoprotein particle receptor activity Important in Cell Biology?
Low-density lipoprotein particle receptor activity is important because it sits at the interface between circulating lipoproteins and cellular cholesterol metabolism. Atherogenic LDL is a major contributor to cardiovascular risk, and the receptors that mediate its uptake determine how much LDL is cleared from the blood and how much cholesterol enters cells. The activity is rapidly regulated in human fibroblasts and arterial smooth muscle cells, showing that it is a responsive node in lipid homeostasis rather than a fixed property. In cancer, LDL receptor activity has been linked to the cholesterol requirements of intracranial tumors and to LRP5/6-dependent progression and immune escape in endometrial cancer, making it a potential target for mechanistic and therapeutic studies. Dietary and natural-compound studies further show that LDL receptor activity can be modulated, for example by n-3 fatty acids in HepG2 cells and by quercetin in vascular endothelial cells.
• Defines a core molecular function for receptor-mediated LDL uptake and endocytosis.
• Directly influences plasma cholesterol handling and atherogenic LDL burden.
• Is rapidly regulated in human fibroblasts, making it a model for feedback control of lipid uptake.
• Is active and regulated in human arterial smooth muscle cells, linking it to vascular disease.
• Is measurable in human intracranial tumors and relates to tumor cholesterol demand.
• Connects to LRP5/6 signaling in endometrial cancer progression and immune escape.
• Can be modulated by dietary factors such as n-3 fatty acids in HepG2 cells.
• Can be influenced by natural compounds such as quercetin in vascular endothelial cells.
• Provides a functional readout for CRISPR knockout, knock-in, and overexpression experiments.
• Supports drug and nutraceutical discovery aimed at lipoprotein clearance pathways.
Molecular Mechanism of low-density lipoprotein particle receptor activity
Ligand recognition and binding
In simple terms: The receptor first has to recognize and grab an LDL particle outside the cell.
The activity begins with the receptor combining with a low-density lipoprotein particle at the cell surface, as specified in the GO:0005041 definition. This binding step is the selective recognition event that distinguishes LDL particles from other extracellular cargo. Studies of LDL uptake describe both holoparticle and cholesteryl ester selective uptake routes, indicating that receptor-mediated recognition can lead to different downstream fates depending on the receptor and cell type. In cultured human fibroblasts, this binding capacity is rapidly regulated, showing that the number or availability of functional receptors is itself a controlled variable.
Endocytic delivery of the LDL particle
In simple terms: After binding, the receptor delivers the LDL particle into the cell by endocytosis.
The defining output of GO:0005041 is delivery of the low-density lipoprotein particle into the cell via endocytosis. This step converts extracellular LDL into an intracellular cargo and is the functional endpoint that distinguishes receptor activity from mere adhesion. The process is part of the broader biology of LDL uptake, which includes holoparticle uptake as well as selective cholesteryl ester uptake. Because endocytic delivery is required for the function, assays that measure internalization are central to studying GO:0005041.
Regulation by cellular cholesterol status
In simple terms: The cell can speed up or slow down LDL receptor activity depending on how much cholesterol it needs.
LDL receptor activity is rapidly regulated in cultured human fibroblasts, demonstrating acute feedback control of this molecular function. This regulation ensures that LDL uptake matches cellular cholesterol requirements. In cultured human arterial smooth muscle cells, LDL receptor activity is also regulated, extending the principle to vascular cell types relevant to atherosclerosis. Together, these observations show that GO:0005041 is a dynamic activity embedded in cholesterol-sensing circuits rather than a constitutive housekeeping function.
Modulation by extracellular and dietary factors
In simple terms: What the cell is exposed to, such as fatty acids or plant compounds, can change LDL receptor activity.
LDL from humans supplemented with n-3 fatty acids depresses both LDL receptor activity and LDLr mRNA abundance in HepG2 cells, showing that the lipid composition of the ligand and dietary context can modulate this function. Quercetin ameliorates atherosclerosis by inhibiting inflammation of vascular endothelial cells via Piezo1 channels, indicating that natural compounds can influence vascular pathways relevant to lipoprotein handling. These findings support the idea that GO:0005041 is responsive to both endogenous and exogenous signals.
Relevance to tumor cholesterol demand
In simple terms: Fast-growing tumor cells may need more LDL uptake to support their growth.
Low-density lipoprotein receptor activity has been measured in human intracranial tumors and related to the cholesterol requirement of those tumors. This suggests that some cancer cells may upregulate or depend on LDL uptake to meet biosynthetic demands. In endometrial cancer, LRP5/6 signaling promotes progression and cancer cell immune escape, linking LDL receptor-related pathways to oncogenic behavior. These observations broaden the functional significance of GO:0005041 beyond cardiovascular biology.
Key Genes Involved in GO:0005041 low-density lipoprotein particle receptor activity
The following genes and proteins are directly or functionally associated with low-density lipoprotein particle receptor activity and its related biology.
| Gene | Major Role | Research Relevance |
|---|---|---|
| LDLR | Classic receptor mediating LDL binding and endocytic uptake | Central to GO:0005041 assays and cholesterol homeostasis studies |
| LRP5 | LDL receptor-related protein involved in signaling | Implicated in endometrial cancer progression and immune escape |
| LRP6 | LDL receptor-related protein involved in signaling | Implicated in endometrial cancer progression and immune escape |
| PCSK9 | Regulates LDL receptor availability | Modulates LDL receptor activity and cholesterol clearance |
| APOB | Structural component of LDL particles | Ligand identity for receptor binding and uptake |
| APOE | Lipoprotein ligand involved in receptor-mediated uptake | Relevant to lipoprotein clearance and cardiovascular risk |
| Piezo1 | Mechanosensitive channel in vascular endothelial cells | Linked to quercetin effects on atherosclerosis and endothelial inflammation |
| SCARB1 | Scavenger receptor for selective cholesteryl ester uptake | Contrasts with holoparticle LDL receptor uptake |
| INSIG1 | Sterol-sensing regulator of lipid synthesis | Indirectly influences cholesterol status and LDL receptor regulation |
| SREBF2 | Transcription factor controlling cholesterol homeostasis | Regulates genes that feed back on LDL uptake |
| HMGCR | Rate-limiting enzyme of cholesterol synthesis | Cholesterol status affects LDL receptor activity |
| NR1H2 | Nuclear receptor involved in lipid metabolism | Modulates cholesterol handling and receptor activity |
| NR1H3 | Nuclear receptor involved in lipid metabolism | Modulates cholesterol handling and receptor activity |
| ABCA1 | Cholesterol efflux transporter | Balances cellular cholesterol and LDL uptake |
| ABCG1 | Cholesterol efflux transporter | Balances cellular cholesterol and LDL uptake |
| CYP7A1 | Bile acid synthesis enzyme | Links cholesterol disposal to LDL receptor demand |
| MYLIP | E3 ubiquitin ligase regulating LDL receptor stability | Controls LDL receptor protein levels |
How Is low-density lipoprotein particle receptor activity Regulated?
Low-density lipoprotein particle receptor activity is regulated at multiple levels. In cultured human fibroblasts, the activity is rapidly regulated, indicating acute feedback control by cellular cholesterol status. In cultured human arterial smooth muscle cells, LDL receptor activity is also regulated, showing that vascular cells can adjust this function. At the ligand level, LDL from humans supplemented with n-3 fatty acids depresses both LDL receptor activity and LDLr mRNA abundance in HepG2 cells, demonstrating that dietary lipid composition can influence receptor function and expression. In vascular endothelial cells, quercetin ameliorates atherosclerosis by inhibiting inflammation via Piezo1 channels, providing an example of pharmacological or natural-compound modulation of pathways relevant to lipoprotein handling. These layers of regulation ensure that GO:0005041 responds to metabolic demand and external signals.
low-density lipoprotein particle receptor activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| LDLR | Atherosclerosis and cardiovascular risk | LDLR knockout HepG2 or fibroblast cells with LDL uptake assays |
| LRP5 | Endometrial cancer progression and immune escape | LRP5 knockout endometrial cancer cell lines with proliferation and immune assays |
| LRP6 | Endometrial cancer progression and immune escape | LRP6 knockout endometrial cancer cell lines with signaling readouts |
| Piezo1 | Vascular endothelial inflammation in atherosclerosis | Piezo1 knockout endothelial cells treated with quercetin |
| LDLR | Intracranial tumor cholesterol requirement | Patient-derived intracranial tumor cells with LDL receptor activity assays |
Atherosclerosis and cardiovascular risk
Atherogenic low-density lipoprotein is a major contributor to cardiovascular risk, and the receptors that mediate LDL uptake are central to this relationship. Low-density lipoprotein particle receptor activity determines how much LDL is cleared from circulation and how much cholesterol enters vascular cells. Cultured human arterial smooth muscle cells regulate LDL receptor activity, linking this molecular function directly to the vascular wall biology that underlies atherosclerosis. Natural compounds such as quercetin can ameliorate atherosclerosis by inhibiting inflammation of vascular endothelial cells via Piezo1 channels, highlighting modifiable pathways connected to lipoprotein handling.
Cancer and tumor cholesterol demand
Low-density lipoprotein receptor activity has been detected in human intracranial tumors and related to their cholesterol requirement, suggesting that tumor cells may rely on LDL uptake for growth. In endometrial cancer, LRP5/6 signaling promotes progression and cancer cell immune escape, connecting LDL receptor-related proteins to oncogenic and immune-evasion mechanisms. These findings indicate that GO:0005041 is not limited to cardiovascular disease but may also be relevant to tumor biology and immunotherapy research.
Metabolic and dietary modulation
LDL from humans supplemented with n-3 fatty acids depresses both LDL receptor activity and LDLr mRNA abundance in HepG2 cells, showing that dietary factors can directly influence this function. This connects GO:0005041 to nutritional and metabolic research, where the goal may be to modulate receptor activity for therapeutic or preventive benefit. Because the activity is rapidly regulated in human fibroblasts, it is also a useful readout for studying cellular cholesterol feedback in metabolic disease models.
From low-density lipoprotein particle receptor activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of LDLR abolish LDL particle uptake? | LDLR knockout cell line with fluorescent LDL uptake assay |
| Does a point mutation in the ligand-binding domain alter receptor activity? | Point-mutation knock-in of LDLR with binding and endocytosis assays |
| Can a tagged receptor be used to track endocytic delivery? | Tagged knock-in of LDLR with imaging and biochemical fractionation |
| Does overexpression of LRP5/6 enhance cancer cell immune escape? | LRP5/6 overexpression in endometrial cancer cells with immune co-culture |
| Does dietary lipid composition change receptor expression? | HepG2 cells treated with n-3 fatty acid-supplemented LDL with mRNA and activity readouts |
| Does a natural compound modulate vascular LDL handling? | Endothelial cells with Piezo1 knockout and quercetin treatment |
How to Study the low-density lipoprotein particle receptor activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Fluorescent LDL uptake assay | Internalization of labeled LDL particles | Validating LDL receptor activity in knockout or overexpression cells |
| Ligand binding assay | Binding affinity and specificity for LDL | Characterizing receptor variants and point mutations |
| qPCR or RNA-seq | LDLR and related gene mRNA abundance | Detecting transcriptional regulation by diet or compounds |
| Western blot | Receptor protein levels | Assessing post-transcriptional regulation of LDL receptor |
| Cell proliferation assay | Growth of cancer cells with altered LRP5/6 | Studying endometrial cancer progression |
| Immune co-culture assay | Cancer cell immune escape | Testing LRP5/6 effects on immune evasion |
| Cholesterol quantification | Cellular cholesterol content | Linking LDL uptake to cholesterol homeostasis |
| Imaging of endocytic trafficking | Localization and delivery of receptor-ligand complexes | Tracking endocytic delivery in tagged knock-in cells |
Ligand binding and uptake assays
Direct measurement of low-density lipoprotein particle receptor activity relies on assays that quantify binding and internalization of LDL particles. The original characterization of LDL uptake described both holoparticle and cholesteryl ester selective uptake, providing a framework for distinguishing receptor-mediated routes. In cultured human fibroblasts, rapid regulation of LDL receptor activity was demonstrated using such assays, establishing a classic experimental paradigm. These methods remain the gold standard for validating GO:0005041 in any cell model.
Gene expression and mRNA abundance analysis
Because receptor activity can be regulated at the level of mRNA abundance, expression analysis is a key complementary method. In HepG2 cells, LDL from humans supplemented with n-3 fatty acids depressed both LDL receptor activity and LDLr mRNA abundance, showing that activity and transcript levels can be measured together. This approach helps distinguish transcriptional regulation from post-transcriptional or post-translational control of GO:0005041.
Cell-based disease models
Disease-relevant cell models allow researchers to study GO:0005041 in context. Cultured human arterial smooth muscle cells regulate LDL receptor activity, making them suitable for vascular biology studies. Human intracranial tumor cells have measurable LDL receptor activity related to cholesterol requirement, supporting cancer metabolism research. Endometrial cancer models with LRP5/6 manipulation can be used to study progression and immune escape. Vascular endothelial cells treated with quercetin provide a model for inflammation and atherosclerosis research.
CRISPR-based functional genomics
CRISPR knockout, point-mutation, knock-in, and overexpression models enable causal testing of genes associated with GO:0005041. For example, LRP5/6 knockout or overexpression in endometrial cancer cells can test their role in progression and immune escape. LDLR knockout or tagged knock-in in hepatic or fibroblast cells can test effects on LDL uptake and endocytic delivery. These approaches connect genotype to the molecular function defined by GO:0005041.
How CRISPR Can Be Used to Study GO:0005041 low-density lipoprotein particle receptor activity
Knockout
CRISPR knockout of LDLR or related genes is used to eliminate low-density lipoprotein particle receptor activity and measure the consequences for LDL uptake and cholesterol homeostasis. Knockout of LRP5 or LRP6 in endometrial cancer cells can test their role in progression and immune escape. These models provide clean loss-of-function evidence for GO:0005041 in disease-relevant contexts.
Point Mutation
Point-mutation models allow precise testing of residues required for LDL binding or endocytic delivery. By introducing specific mutations into LDLR or related receptors, researchers can dissect which domains are essential for GO:0005041. Such models are valuable when complete knockout is lethal or when subtle functional changes are expected.
Knock-in
Knock-in of tagged or reporter versions of LDLR enables tracking of receptor trafficking and endocytic delivery in live cells. Knock-in of disease-associated variants can also reveal how specific alleles affect low-density lipoprotein particle receptor activity. These models bridge molecular function and disease genetics.
Overexpression
Overexpression of LDLR or LRP5/6 can test whether increased receptor levels enhance LDL uptake or cancer cell immune escape. In endometrial cancer cells, LRP5/6 overexpression promotes progression and immune escape, demonstrating gain-of-function effects. Overexpression models complement knockout studies by revealing sufficiency rather than necessity.
How EDITGENE Supports low-density lipoprotein particle receptor activity Research
Researchers studying low-density lipoprotein particle receptor activity-related genes often need to determine whether a candidate gene is causally involved in LDL binding, endocytic delivery, or downstream disease phenotypes. Establishing causality requires controlled genetic models that can isolate the contribution of a single gene to GO:0005041. EDITGENE provides a comprehensive suite of CRISPR-based services designed to support exactly this kind of mechanistic research.
Contact EDITGENE today to design your custom CRISPR model for low-density lipoprotein particle receptor activity research.
Frequently Asked Questions About low-density lipoprotein particle receptor activity
What is low-density lipoprotein particle receptor activity?
It is the molecular function defined by GO:0005041, in which a receptor combines with a low-density lipoprotein particle and delivers it into the cell via endocytosis.
What is the GO ID for low-density lipoprotein particle receptor activity?
The GO ID is GO:0005041, and it belongs to the molecular_function ontology.
What genes are involved in low-density lipoprotein particle receptor activity?
Key genes include LDLR, LRP5, LRP6, PCSK9, APOB, APOE, and other lipid metabolism genes.
How is LDL receptor activity regulated?
It is rapidly regulated in human fibroblasts and arterial smooth muscle cells, and can be modulated by dietary factors such as n-3 fatty acids.
Is LDL receptor activity relevant to cancer?
Yes, LDL receptor activity has been measured in human intracranial tumors and LRP5/6 signaling is implicated in endometrial cancer progression and immune escape.
What diseases are associated with low-density lipoprotein particle receptor activity?
Atherosclerosis and cardiovascular risk are strongly associated, and cancer biology is an emerging area of relevance.
How can I study low-density lipoprotein particle receptor activity in the lab?
Common methods include fluorescent LDL uptake assays, ligand binding assays, qPCR, Western blot, and CRISPR-based genetic models.
What CRISPR models are useful for studying GO:0005041?
Knockout, point-mutation, knock-in, and overexpression models of LDLR, LRP5, and LRP6 are all useful for dissecting this function.
Can diet affect LDL receptor activity?
Yes, LDL from humans supplemented with n-3 fatty acids depresses both LDL receptor activity and LDLr mRNA abundance in HepG2 cells.
What natural compounds affect pathways related to LDL receptor activity?
Quercetin ameliorates atherosclerosis by inhibiting inflammation of vascular endothelial cells via Piezo1 channels, which is relevant to vascular lipoprotein handling.
Conclusion
GO:0005041, low-density lipoprotein particle receptor activity, is a well-defined molecular function that governs how cells bind and internalize LDL particles. Its rapid regulation in human fibroblasts and arterial smooth muscle cells, its modulation by dietary factors, and its relevance to atherosclerosis and cancer make it a high-value target for mechanistic research. CRISPR-based knockout, point-mutation, knock-in, and overexpression models provide the causal tools needed to dissect this function in disease-relevant cell types.
References
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- 3. Wang YM et al.. 2024. Quercetin ameliorates atherosclerosis by inhibiting inflammation of vascular endothelial cells via Piezo1 channels.. Phytomedicine 132:155865 PMID: 39004029
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- 5. Oram JF et al.. 1980. Rapid regulation of the activity of the low density lipoprotein receptor of cultured human fibroblasts.. J Biol Chem 255(2):475-85 PMID: 7356627
- 6. Rudling MJ et al.. 1990. Low density lipoprotein receptor activity in human intracranial tumors and its relation to the cholesterol requirement.. Cancer Res 50(3):483-7 PMID: 2297691
- 7. Lindsey S et al.. 1992. Low density lipoprotein from humans supplemented with n-3 fatty acids depresses both LDL receptor activity and LDLr mRNA abundance in HepG2 cells.. J Lipid Res 33(5):647-58 PMID: 1535648
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