GO:0050252 retinol O-fatty-acyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0050252 (retinol O-fatty-acyltransferase activity) catalyzes the transfer of a fatty acyl group from acyl-CoA to retinol, producing retinyl ester and CoA.
• This enzymatic activity is present in multiple tissues, including liver, small intestine, retinal pigment epithelium, lacrimal gland, epidermis, and Müller cells [2,4,5,6,7,8,1].
• The reaction is a key step in vitamin A storage, converting retinol into retinyl esters for storage in lipid droplets and for visual chromophore regeneration [7,5].
• Enzyme activity is regulated by vitamin A status, as shown by increased hepatic lecithin:retinol acyltransferase activity in vitamin A-deficient rats.
• Several enzymes exhibit this activity, including LRAT, DGAT1, and AWAT2, with overlapping substrate specificities [3,4,7].
• Studying GO:0050252 helps researchers understand retinoid metabolism, vision, skin barrier function, and diseases linked to vitamin A dysregulation [5,3,8].
Description
Retinol O-fatty-acyltransferase activity (GO:0050252) is a molecular function that catalyzes the esterification of retinol with a fatty acyl group donated by acyl-CoA, yielding retinyl ester and coenzyme A. This reaction is central to vitamin A metabolism because it converts retinol, a reactive alcohol, into more stable and storage-friendly retinyl esters. The activity has been detected in microsomes from rat liver, rat small intestine, bovine retinal pigment epithelium, chicken Müller cells, mouse epidermis, and rabbit lacrimal gland, indicating a broad tissue distribution [7,4,5,1,8,6]. Researchers study this activity to understand how cells manage vitamin A storage, supply the visual cycle, and maintain epithelial barriers [5,8,3]. The enzyme(s) responsible include lecithin:retinol acyltransferase (LRAT), acyl-CoA:retinol acyltransferase (ARAT), and multifunctional O-acyltransferases such as DGAT1 and AWAT2, which can also synthesize acylglycerols and waxes [4,7,3]. Because retinyl esters are the main storage form of vitamin A in the body, dysregulation of this activity can affect vision, skin health, and systemic retinoid homeostasis [5,8,2].
retinol O-fatty-acyltransferase activity At A Glance
| GO ID | GO:0050252 |
|---|---|
| GO term | retinol O-fatty-acyltransferase activity |
| Ontology | molecular_function |
| Synonym | acyl-CoA:retinol O-acyltransferase activity; retinol acyltransferase activity; retinol fatty-acyltransferase activity |
| Major function | Catalyzes the transfer of a fatty acyl group from acyl-CoA to retinol, producing retinyl ester and CoA |
| Tissue distribution | Liver, small intestine, retinal pigment epithelium, lacrimal gland, epidermis, Müller cells [7,4,5,6,8,1] |
| Key enzymes | LRAT (with acyl-CoA as donor in some contexts), ARAT, DGAT1, AWAT2 [4,7,3] |
| Regulation | Activity is regulated by vitamin A status; hepatic LRAT activity increases in vitamin A deficiency |
| Related pathway | Retinoid metabolism, visual cycle, lipid storage [5,7] |
What Is GO:0050252?
According to the Gene Ontology, GO:0050252 (retinol O-fatty-acyltransferase activity) is defined as the catalysis of the reaction: acyl-CoA + retinol = CoA + retinyl ester. In other words, it is an enzymatic activity that transfers a fatty acid from an acyl-CoA donor to the hydroxyl group of retinol, forming a retinyl ester and releasing coenzyme A. This activity is synonymous with acyl-CoA:retinol O-acyltransferase activity, retinol acyltransferase activity, and retinol fatty-acyltransferase activity. It belongs to the molecular_function ontology aspect and is distinct from lecithin:retinol acyltransferase (LRAT) activity, which uses phosphatidylcholine as the acyl donor rather than acyl-CoA.
Why Is retinol O-fatty-acyltransferase activity Important in Cell Biology?
GO:0050252 is important because it represents a key enzymatic step in vitamin A storage and retinoid homeostasis. By converting retinol to retinyl esters, this activity prevents retinol toxicity and provides a readily mobilizable pool of vitamin A for processes such as vision, cell differentiation, and immune function [7,5]. In the eye, retinyl ester synthesis in the retinal pigment epithelium is essential for the visual cycle, and defects in this process can lead to retinal degeneration. In the skin, retinyl esters contribute to barrier function and are used in dermatological treatments [8,3]. In the liver, the activity is dynamically regulated by vitamin A status, helping to maintain systemic retinol levels. Therefore, understanding GO:0050252 has implications for nutrition, ophthalmology, dermatology, and metabolic diseases.
• Enables storage of vitamin A as retinyl esters in lipid droplets, preventing retinol toxicity.
• Supplies retinyl esters for the visual cycle in the retinal pigment epithelium.
• Contributes to skin barrier function and epidermal differentiation [8,3].
• Is regulated by vitamin A status, linking diet to retinoid metabolism.
• Plays a role in intestinal absorption and chylomicron assembly.
• Involved in lacrimal gland function and tear film stability.
• Provides a target for modulating retinoid levels in dermatological conditions.
• Helps maintain systemic retinol homeostasis through hepatic storage.
• May influence energy balance and lipid metabolism through multifunctional O-acyltransferases.
• Dysregulation may contribute to diseases such as night blindness and dry eye [5,6].
What Happens During retinol O-fatty-acyltransferase activity?
Substrate Binding and Acyl Transfer
In simple terms: The enzyme grabs a fatty acid from acyl-CoA and attaches it to retinol.
The reaction begins with the binding of acyl-CoA and retinol to the enzyme active site. The enzyme catalyzes the transfer of the fatty acyl group from acyl-CoA to the hydroxyl group of retinol, forming a retinyl ester and releasing coenzyme A. This two-substrate mechanism is characteristic of O-acyltransferases, and the reaction is reversible in vitro but favors ester formation under physiological conditions.
Tissue-Specific Isoforms and Localization
In simple terms: Different tissues use different enzymes to do this job.
In the liver and small intestine, microsomal ARAT activity esterifies retinol for storage and secretion [7,4]. In the retinal pigment epithelium, ARAT activity provides retinyl esters for the visual cycle. In the lacrimal gland, the activity helps produce retinyl esters for tear film. In the epidermis, ARAT activity contributes to the retinyl ester pool in skin. In Müller cells, 11-cis-retinol can be esterified by an acyl-CoA:retinol O-acyltransferase.
Role in Vitamin A Storage and Mobilization
In simple terms: This reaction packs vitamin A into a storage form that can be used later.
Retinyl esters formed by GO:0050252 are stored in lipid droplets within cells. When vitamin A is needed, retinyl esters are hydrolyzed back to retinol, which can then be converted to active metabolites such as retinoic acid or retinal. This storage-and-release cycle is critical for maintaining steady retinol levels, especially in times of dietary fluctuation.
Regulation by Vitamin A Status
In simple terms: When vitamin A is low, the body adjusts the enzyme activity to conserve it.
Hepatic lecithin:retinol acyltransferase (LRAT) activity, which shares the same overall goal of retinol esterification, is regulated by vitamin A status. In vitamin A-deficient rats, hepatic LRAT activity increases, suggesting a compensatory mechanism to store any available retinol. Although LRAT uses phosphatidylcholine as an acyl donor, the regulation of retinol esterification highlights the importance of maintaining retinyl ester pools.
Key Genes Involved in GO:0050252 retinol O-fatty-acyltransferase activity
The following genes and proteins are directly or indirectly associated with retinol O-fatty-acyltransferase activity (GO:0050252) based on published biochemical and molecular studies.
| Gene | Major Role | Research Relevance |
|---|---|---|
| LRAT | Lecithin:retinol acyltransferase; transfers acyl group from phosphatidylcholine to retinol, but also exhibits acyl-CoA-dependent activity in some contexts [4,7] | Key enzyme for retinyl ester synthesis; mutations cause retinal degeneration and vitamin A deficiency symptoms |
| DGAT1 | Diacylglycerol O-acyltransferase 1; multifunctional O-acyltransferase that can synthesize retinyl esters using acyl-CoA | Links retinoid metabolism to lipid storage; target for obesity and skin research |
| AWAT2 | Acyl-CoA wax alcohol acyltransferase 2; also known as MFAT, catalyzes synthesis of waxes, acylglycerols, and retinyl esters | Important for skin barrier and retinoid esterification in epidermis |
| ARAT (activity) | Acyl-CoA:retinol acyltransferase activity; not a single gene but enzymatic activity attributed to multiple enzymes | Measured in liver, intestine, RPE, lacrimal gland, epidermis [7,4,5,6,8] |
| RPE65 | Retinal pigment epithelium-specific 65 kDa protein; involved in visual cycle, indirectly related to retinyl ester pools | Mutations cause Leber congenital amaurosis; research on retinyl ester metabolism |
| CRBP1 | Cellular retinol-binding protein 1; delivers retinol to esterifying enzymes | Modulates substrate availability for ARAT |
| CRBP2 | Cellular retinol-binding protein 2; intestinal retinol binding | Facilitates retinol esterification in small intestine |
| PNPLA4 | Patatin-like phospholipase domain-containing protein 4; may hydrolyze retinyl esters | Balances retinyl ester storage and mobilization |
| CYP26A1 | Cytochrome P450 family 26 subfamily A member 1; degrades retinoic acid | Indirectly affects retinol pools available for esterification |
| ALDH1A1 | Aldehyde dehydrogenase 1 family member A1; oxidizes retinal to retinoic acid | Competes with esterification for retinol |
| RDH10 | Retinol dehydrogenase 10; oxidizes retinol to retinal | Regulates retinol availability for esterification |
| LRAT (isoforms) | Different splice variants may have distinct tissue distribution | Isoform-specific functions in liver vs. intestine |
| DGAT2 | Diacylglycerol O-acyltransferase 2; may contribute to retinyl ester synthesis in some tissues | Potential redundancy with DGAT1 |
| MGAT | Monoacylglycerol O-acyltransferase; may esterify retinol in intestine | Intestinal retinyl ester synthesis |
| SOAT | Sterol O-acyltransferase; can esterify retinol in vitro | Broad substrate specificity of O-acyltransferases |
| ACAT1 | Acetyl-CoA acetyltransferase 1; not directly involved but related to acyl-CoA pools | Acyl-CoA supply for esterification |
| SLC27A4 | Fatty acid transport protein 4; affects acyl-CoA availability | Indirect role in substrate supply |
| ABCA1 | ATP-binding cassette transporter A1; involved in lipid efflux, may affect retinyl ester transport | Link to lipoprotein metabolism |
How Is retinol O-fatty-acyltransferase activity Regulated?
The activity of retinol O-fatty-acyltransferase is regulated by vitamin A status. In rats, hepatic lecithin:retinol acyltransferase (LRAT) activity, which shares the same physiological role of retinol esterification, is increased in vitamin A deficiency, suggesting a feedback mechanism to conserve retinol. Additionally, the availability of substrates (retinol and acyl-CoA) and the expression of enzymes such as LRAT, DGAT1, and AWAT2 influence the overall rate of retinyl ester synthesis [3,7]. Hormonal and nutritional factors may also modulate activity, but specific pathways remain to be fully elucidated.
retinol O-fatty-acyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| LRAT | Retinal dystrophy, vitamin A deficiency | LRAT knockout mouse, patient-derived iPSC-RPE |
| DGAT1 | Skin barrier defects, obesity | DGAT1 knockout mouse, keratinocyte-specific KO |
| AWAT2 | Dry skin, impaired barrier | AWAT2 knockout mouse, 3D skin equivalents |
| ARAT (activity) | Night blindness, dry eye | ARAT activity assays in RPE and lacrimal gland [5,6] |
| CRBP1 | Vitamin A metabolism disorders | CRBP1 knockout mouse |
Retinal Degeneration and Visual Cycle Defects
Retinyl ester synthesis in the retinal pigment epithelium is essential for the visual cycle. Enzymes exhibiting retinol O-fatty-acyltransferase activity, such as ARAT, contribute to the retinyl ester pool that is used to regenerate 11-cis-retinal. Defects in this process can lead to impaired vision and retinal degeneration. For example, mutations in LRAT, which can also catalyze retinol esterification, cause early-onset retinal dystrophy. Studying GO:0050252 helps understand how retinyl ester metabolism supports photoreceptor function.
Skin Barrier Dysfunction and Dermatological Conditions
In the epidermis, retinol esterification is important for maintaining the retinyl ester pool that can be converted to retinoic acid for regulating keratinocyte differentiation. Multifunctional O-acyltransferases such as AWAT2 and DGAT1 contribute to this activity and also synthesize waxes and acylglycerols essential for the skin barrier. Dysregulation may lead to dry skin, impaired barrier function, and inflammatory skin diseases. Research on GO:0050252 provides insights into dermatological therapies using retinoids [3,8].
Vitamin A Deficiency and Systemic Retinoid Homeostasis
The liver is a major site of retinol esterification, storing vitamin A as retinyl esters. The activity of ARAT and LRAT in the liver is regulated by vitamin A status, with increased activity during deficiency to maximize storage. Impaired esterification can lead to reduced vitamin A reserves, contributing to night blindness, immune dysfunction, and developmental defects. Understanding GO:0050252 is therefore relevant to nutritional and metabolic disorders [2,7].
Dry Eye and Lacrimal Gland Dysfunction
The lacrimal gland esterifies retinol, and this activity is thought to contribute to the production of retinyl esters in tears, which may protect the ocular surface. Alterations in retinol esterification could affect tear film stability and lead to dry eye syndrome. Studying GO:0050252 in lacrimal gland models may reveal new therapeutic targets.
From retinol O-fatty-acyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of ARAT activity affect retinyl ester stores? | Knockout of candidate genes (e.g., LRAT, DGAT1) in cell lines or mice [5,3] |
| Does a point mutation alter substrate specificity? | Point mutation knock-in using CRISPR in HEK293 or RPE cells |
| Can we tag the enzyme to track localization? | Knock-in of fluorescent tag (e.g., GFP) at endogenous locus |
| Does overexpression increase retinyl ester synthesis? | Overexpression of LRAT, DGAT1, or AWAT2 in cultured cells |
| Which genes regulate retinol esterification? | CRISPR library screening in retinoid-responsive reporter cells |
| How does vitamin A status affect activity? | Dietary manipulation in rodent models |
How to Study the retinol O-fatty-acyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled activity assay | Enzyme activity using [3H]retinol and acyl-CoA | Quantify ARAT activity in tissue microsomes [7,4] |
| HPLC or LC-MS | Retinyl ester species and quantities | Measure products in cells and tissues [3,7] |
| CRISPR knockout | Loss-of-function effects on retinyl ester synthesis | Validate gene function in cell lines [5,3] |
| CRISPR knock-in | Tagged protein localization or point mutations | Study enzyme trafficking and catalytic residues |
| RNA-seq | Transcriptional changes in retinoid metabolism | Identify co-regulated genes |
| CRISPR library screening | Genome-wide modifiers of retinyl ester levels | Discover novel regulators |
| Immunofluorescence | Subcellular localization of enzymes | Visualize enzyme distribution |
| Lipid droplet imaging | Storage of retinyl esters | Assess vitamin A storage dynamics |
Enzymatic Activity Assays
Retinol O-fatty-acyltransferase activity is typically measured using radiolabeled retinol and acyl-CoA donors, followed by extraction and separation of retinyl esters by thin-layer chromatography or high-performance liquid chromatography [7,4]. These assays can be performed on microsomal fractions from tissues or cultured cells and are used to quantify enzyme kinetics and substrate specificity [7,5].
CRISPR-Cas9 Genome Editing
CRISPR-Cas9 can be used to generate knockout, point mutation, or knock-in models to study the function of genes encoding retinol O-fatty-acyltransferase activity. For example, knocking out LRAT or DGAT1 in cell lines allows researchers to assess their contribution to retinyl ester synthesis [3,5]. Point mutations can be introduced to test catalytic residues, and tagged knock-ins enable localization studies.
Lipidomics and Mass Spectrometry
Mass spectrometry-based lipidomics can quantify retinyl esters and other lipids in cells and tissues. This approach is valuable for measuring the products of GO:0050252 and understanding how genetic or pharmacological perturbations affect retinoid storage [3,7].
Transcriptomics and Bioinformatics
RNA sequencing and bioinformatics analyses can identify genes co-expressed with retinol O-fatty-acyltransferase activity, revealing regulatory networks and potential disease associations. CRISPR library screening combined with next-generation sequencing can pinpoint genes that modulate retinyl ester levels.
How CRISPR Can Be Used to Study GO:0050252 retinol O-fatty-acyltransferase activity
Knockout
CRISPR knockout of genes encoding retinol O-fatty-acyltransferase activity, such as LRAT, DGAT1, or AWAT2, can abolish or reduce retinyl ester synthesis in cells. These models are used to determine the contribution of each enzyme to total activity and to study downstream effects on retinoid signaling and lipid metabolism [5,3].
Point Mutation
Point mutations can be introduced into catalytic residues or substrate-binding sites of candidate enzymes to dissect their mechanism. For example, mutating the active-site serine of LRAT or DGAT1 can clarify its role in acyl transfer. Such models help confirm whether a specific gene product is responsible for GO:0050252.
Knock-in
Knock-in of epitope tags (e.g., FLAG, GFP) at endogenous loci allows for tracking enzyme expression, localization, and interaction partners. This is particularly useful for studying the subcellular site of retinyl ester synthesis, such as the endoplasmic reticulum or lipid droplets.
Overexpression
Overexpression of LRAT, DGAT1, or AWAT2 in cultured cells can increase retinyl ester production and is used to study the consequences of enhanced retinol esterification on cell physiology, including lipid droplet formation and retinoic acid availability [3,7].
How EDITGENE Supports retinol O-fatty-acyltransferase activity Research
Researchers studying retinol O-fatty-acyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in retinyl ester synthesis, how mutations affect enzyme function, and what downstream pathways are impacted. EDITGENE provides a comprehensive suite of CRISPR-based services to address these questions with precision and scale.
Contact EDITGENE today to design your custom CRISPR model for retinol O-fatty-acyltransferase activity research.
Frequently Asked Questions About retinol O-fatty-acyltransferase activity
What is retinol O-fatty-acyltransferase activity?
It is an enzymatic activity (GO:0050252) that catalyzes the transfer of a fatty acyl group from acyl-CoA to retinol, forming retinyl ester and coenzyme A.
What genes are involved in retinol O-fatty-acyltransferase activity?
Genes encoding enzymes with this activity include LRAT, DGAT1, and AWAT2, although LRAT primarily uses phosphatidylcholine as an acyl donor [4,3].
Which tissues express retinol O-fatty-acyltransferase activity?
Activity has been detected in liver, small intestine, retinal pigment epithelium, lacrimal gland, epidermis, and Müller cells [7,4,5,6,8,1].
How is retinol O-fatty-acyltransferase activity regulated?
It is regulated by vitamin A status; hepatic LRAT activity increases in vitamin A deficiency, and substrate availability and enzyme expression also modulate activity [2,3].
What diseases are associated with defects in retinol esterification?
Defects can contribute to retinal degeneration, dry eye, skin barrier dysfunction, and systemic vitamin A deficiency symptoms [5,6,3,2].
What is the difference between ARAT and LRAT?
ARAT uses acyl-CoA as the acyl donor, while LRAT uses phosphatidylcholine; both esterify retinol but are distinct enzymatic activities [7,4].
How can I measure retinol O-fatty-acyltransferase activity in the lab?
Common methods include radiolabeled activity assays with [3H]retinol and acyl-CoA, followed by HPLC or thin-layer chromatography to detect retinyl esters [7,4].
Can CRISPR be used to study retinol O-fatty-acyltransferase activity?
Yes, CRISPR knockout, knock-in, and point mutation models can be used to dissect the function of genes like LRAT, DGAT1, and AWAT2 in retinyl ester synthesis [5,3].
What is the role of retinol O-fatty-acyltransferase activity in vision?
In the retinal pigment epithelium, it produces retinyl esters that are essential for the visual cycle and regeneration of 11-cis-retinal.
Are there therapeutic implications of targeting this activity?
Modulating retinol esterification could affect skin conditions, retinal diseases, and vitamin A-related disorders, making it a potential drug target [3,5,2].
Conclusion
Retinol O-fatty-acyltransferase activity (GO:0050252) is a fundamental enzymatic function in vitamin A metabolism, responsible for converting retinol into storage-friendly retinyl esters. Its presence across diverse tissues underscores its importance in vision, skin barrier function, intestinal absorption, and systemic retinoid homeostasis [7,5,4,8]. Dysregulation of this activity is linked to retinal degeneration, dry eye, and nutritional disorders, making it a compelling target for research and therapeutic development [5,6,2]. By leveraging CRISPR-based models and advanced analytical methods, researchers can further unravel the molecular players and regulatory networks controlling this activity, paving the way for new interventions in retinoid-related diseases.
References
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- 3. Yen CL et al.. 2005. A human skin multifunctional O-acyltransferase that catalyzes the synthesis of acylglycerols, waxes, and retinyl esters.. J Lipid Res 46(11):2388-97 PMID: 16106050
- 4. MacDonald PN et al.. 1988. Evidence for a lecithin-retinol acyltransferase activity in the rat small intestine.. J Biol Chem 263(25):12478-82 PMID: 3410848
- 5. Kaschula CH et al.. 2006. Acyl CoA:retinol acyltransferase (ARAT) activity is present in bovine retinal pigment epithelium.. Exp Eye Res 82(1):111-21 PMID: 16054134
- 6. Ubels JL et al.. 1990. Esterification of retinol in lacrimal gland. Evidence for acyl-CoA:retinol acyltransferase activity.. Invest Ophthalmol Vis Sci 31(3):582-9 PMID: 2318596
- 7. Ross AC. 1982. Retinol esterification by rat liver microsomes. Evidence for a fatty acyl coenzyme A: retinol acyltransferase.. J Biol Chem 257(5):2453-9 PMID: 7061433
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