GO:0050253 retinyl-palmitate esterase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0050253 (retinyl-palmitate esterase activity) catalyzes the hydrolysis of retinyl palmitate to retinol and palmitate, a key step in vitamin A mobilization.
• The enzyme is found in liver, retina, and other tissues, and its activity is sensitive to nutritional status such as protein deficiency.
• Retinyl palmitate hydrolase activity is distinct from cholesteryl ester and triacylglycerol hydrolases, although some inhibitors affect all three.
• Spatial distribution of the enzyme in liver changes with vitamin A status, suggesting a role in retinol homeostasis.
• Studying this activity helps understand vitamin A metabolism, vision, and related diseases.
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) enable precise dissection of gene function in retinyl ester metabolism.
Description
Retinyl-palmitate esterase activity (GO:0050253) is a molecular function that catalyzes the hydrolysis of retinyl palmitate into retinol and palmitate. This reaction is essential for mobilizing stored vitamin A from the liver and other tissues, making it a central node in retinoid metabolism. Researchers study this activity to understand how vitamin A is released from its storage form and how defects contribute to disease. The enzyme has been characterized in rat liver, bovine retina, and human liver, revealing species- and tissue-specific properties. Its activity is influenced by nutritional status, such as protein deficiency, and by vitamin A levels. Understanding GO:0050253 provides insight into retinoid biology and potential therapeutic targets.
retinyl-palmitate esterase activity At A Glance
| GO ID | GO:0050253 |
|---|---|
| GO term | retinyl-palmitate esterase activity |
| Ontology | molecular_function |
| Synonym | retinyl ester hydrolase activity; retinyl palmitate hydrolase activity; retinyl palmitate hydrolyase activity; retinyl-palmitate palmitohydrolase activity |
| Major function | Hydrolysis of retinyl palmitate to retinol and palmitate |
| Reaction | retinyl palmitate + H2O = retinol + palmitate + H+ |
| Tissue distribution | Liver, retina, and other tissues |
| Regulation | Influenced by nutritional status and vitamin A levels |
What Is GO:0050253?
According to QuickGO, GO:0050253 (retinyl-palmitate esterase activity) is defined as the catalysis of the reaction: retinyl palmitate + H2O = retinol + palmitate + H+. This activity is also known as retinyl ester hydrolase, retinyl palmitate hydrolase, retinyl palmitate hydrolyase, or retinyl-palmitate palmitohydrolase. It belongs to the molecular_function ontology and is involved in the release of retinol from its esterified storage form.
Why Is retinyl-palmitate esterase activity Important in Cell Biology?
Retinyl-palmitate esterase activity is critical for vitamin A homeostasis because it liberates retinol from its storage ester, allowing it to be used in vision, cell differentiation, and immune function. Dysregulation of this activity can lead to impaired retinol availability, affecting processes such as vision and embryonic development. The enzyme's distinct properties compared to other neutral hydrolases make it a unique target for studying retinoid metabolism. Its presence in the retina suggests a role in the visual cycle. Moreover, nutritional deficiencies alter its activity, linking it to public health issues like vitamin A deficiency.
• Essential for mobilizing stored vitamin A from the liver.
• Provides retinol for the visual cycle in the retina.
• Distinct from other neutral lipid hydrolases, allowing specific regulation.
• Activity is reduced in protein deficiency, linking nutrition to retinoid status.
• Spatial distribution in liver changes with vitamin A status, indicating adaptive regulation.
• Inhibited by ether analogs of cholesteryl esters and acylglycerides, suggesting shared or overlapping active sites.
• Characterized in human liver, highlighting clinical relevance.
• Potential target for modulating vitamin A levels in disease.
Molecular Mechanism of retinyl-palmitate esterase activity
Substrate Recognition and Binding
In simple terms: The enzyme grabs retinyl palmitate and holds it in place.
Retinyl-palmitate esterase activity specifically recognizes retinyl palmitate as a substrate. Studies in rat liver show that the enzyme can also hydrolyze cholesteryl oleate and triolein, but with different efficiencies, indicating a degree of substrate overlap. The active site likely accommodates the retinyl moiety and the palmitate chain, as inhibition by ether analogs of cholesteryl esters and acylglycerides suggests competition for the same site.
Catalytic Hydrolysis
In simple terms: The enzyme uses water to split the ester bond, releasing retinol and palmitate.
The catalytic mechanism involves hydrolysis of the ester bond, yielding retinol and palmitate. The reaction requires water and produces a proton. The enzyme's activity is optimal under specific pH and temperature conditions, as characterized in rat liver. The reaction is distinct from non-enzymatic hydrolysis due to its protein-mediated catalysis.
Tissue-Specific Isoforms and Distribution
In simple terms: Different tissues have their own versions of the enzyme.
Retinyl-palmitate esterase activity has been detected in rat liver, bovine retina, and human liver. In the retina, the activity is present but may have different properties compared to liver. The spatial distribution in rat liver changes with vitamin A status, suggesting tissue-specific regulation.
Regulation by Nutritional Status
In simple terms: What you eat affects how well the enzyme works.
Protein deficiency in rats leads to decreased hepatic retinyl palmitate hydrolase activity, indicating that nutritional status regulates the enzyme. Vitamin A deficiency also alters the spatial distribution of the enzyme in the liver. These findings highlight the enzyme's responsiveness to systemic metabolic cues.
Key Genes Involved in GO:0050253 retinyl-palmitate esterase activity
The genes encoding retinyl-palmitate esterase activity are not fully identified, but candidate enzymes include known neutral lipases and esterases that exhibit this activity.
| Gene | Major Role | Research Relevance |
|---|---|---|
| LIPE | Hormone-sensitive lipase, exhibits retinyl ester hydrolase activity | Studied in lipid metabolism and retinoid mobilization |
| PNPLA2 | Adipose triglyceride lipase, may hydrolyze retinyl esters | Linked to lipid droplet metabolism |
| PNPLA3 | Patatin-like phospholipase domain-containing protein 3 | Associated with liver disease and retinoid metabolism |
| CES1 | Carboxylesterase 1, hydrolyzes retinyl esters | Expressed in liver, involved in drug and lipid metabolism |
| CES2 | Carboxylesterase 2, may hydrolyze retinyl esters | Intestinal and hepatic expression |
| AADAC | Arylacetamide deacetylase, has retinyl ester hydrolase activity | Studied in liver and intestine |
| ABHD5 | Alpha/beta hydrolase domain-containing protein 5 | Coactivator of ATGL, may influence retinyl ester hydrolysis |
| MGLL | Monoglyceride lipase, broad substrate specificity | Potential role in retinoid metabolism |
| NCEH1 | Neutral cholesterol ester hydrolase 1 | Hydrolyzes cholesteryl esters, may also act on retinyl esters |
| LPL | Lipoprotein lipase | May hydrolyze retinyl esters in lipoproteins |
| APOA1 | Apolipoprotein A1 | Carries retinol-binding protein, indirect role |
| RBP4 | Retinol-binding protein 4 | Transports retinol, not an enzyme but related |
| TTR | Transthyretin | Transports retinol-binding protein |
| STRA6 | Stimulated by retinoic acid 6 | Retinol uptake, not an enzyme |
| LRAT | Lecithin retinol acyltransferase | Synthesizes retinyl esters, reverse reaction |
| DGAT1 | Diacylglycerol O-acyltransferase 1 | May synthesize retinyl esters |
| AWAT2 | Acyl-CoA wax alcohol acyltransferase 2 | Synthesizes retinyl esters in skin |
| CYP26A1 | Cytochrome P450 26A1 | Degrades retinoic acid, indirect |
How Is retinyl-palmitate esterase activity Regulated?
Retinyl-palmitate esterase activity is regulated by nutritional status, particularly protein and vitamin A levels. In protein-deficient rats, hepatic activity decreases, suggesting that enzyme synthesis or activation depends on adequate protein intake. Vitamin A deficiency alters the spatial distribution of the enzyme in the liver, indicating feedback regulation. Additionally, inhibition by ether analogs of cholesteryl esters and acylglycerides suggests that the enzyme's active site can be competitively inhibited. Hormonal and metabolic signals may also influence activity, but specific pathways remain to be fully elucidated.
retinyl-palmitate esterase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| LIPE | Lipid metabolism disorders | Knockout mouse, hepatocyte cell lines |
| PNPLA2 | Neutral lipid storage disease | Knockout models, overexpression |
| PNPLA3 | Non-alcoholic fatty liver disease | Point mutation knock-in (I148M) |
| CES1 | Drug metabolism, obesity | Knockout and overexpression in liver cells |
| RBP4 | Insulin resistance, vitamin A deficiency | Transgenic overexpression |
Vitamin A Deficiency
Vitamin A deficiency is a major public health issue, and retinyl-palmitate esterase activity is crucial for mobilizing stored vitamin A. Reduced activity could exacerbate deficiency symptoms. Animal models of protein deficiency show decreased hepatic activity, linking malnutrition to impaired retinol release.
Retinal Disorders
The presence of retinyl-palmitate esterase activity in the bovine retina suggests a role in the visual cycle. Dysregulation could contribute to retinal degeneration or night blindness, although direct evidence is limited.
Liver Disease
Human liver expresses retinyl-palmitate esterase activity, and changes in its activity may affect hepatic vitamin A storage and release. Conditions such as fatty liver disease could alter retinoid metabolism, but further research is needed.
From retinyl-palmitate esterase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does knockout of a candidate gene reduce retinyl-palmitate esterase activity? | CRISPR knockout in HepG2 or primary hepatocytes |
| Does a specific point mutation affect enzyme kinetics? | CRISPR point mutation knock-in in cell lines |
| Can we tag the enzyme for localization studies? | Knock-in of fluorescent tag (e.g., GFP) at endogenous locus |
| Does overexpression increase retinol release? | CRISPR activation or cDNA overexpression |
| Which genes regulate retinyl ester hydrolysis? | CRISPR library screening with retinyl palmitate substrate |
| How does the enzyme behave in vivo? | Knockout mouse models |
How to Study the retinyl-palmitate esterase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| HPLC-based activity assay | Hydrolysis of retinyl palmitate to retinol | Quantify enzyme activity in tissues |
| RNA-seq | mRNA expression levels | Identify genes co-regulated with activity |
| Western blot | Protein abundance | Validate candidate enzymes |
| CRISPR knockout | Loss-of-function effects | Test gene necessity for activity |
| CRISPR activation | Gain-of-function effects | Test gene sufficiency |
| Fluorescence microscopy | Subcellular localization | Determine organelle targeting |
| Mass spectrometry | Protein identification and modifications | Discover novel enzymes |
Enzymatic Activity Assays
Retinyl-palmitate esterase activity is typically measured using radiolabeled or fluorescent retinyl palmitate as substrate, followed by separation of products via HPLC or thin-layer chromatography. These assays allow quantification of hydrolytic activity in tissue homogenates or purified fractions.
Gene Expression Analysis
RNA-seq and qPCR can measure mRNA levels of candidate genes under conditions that modulate retinyl-palmitate esterase activity, such as vitamin A deficiency or protein restriction.
Proteomics and Immunodetection
Western blotting and mass spectrometry can identify and quantify proteins with retinyl ester hydrolase activity, as well as post-translational modifications that regulate their function.
CRISPR Screening
Genome-wide CRISPR knockout or activation screens coupled with a retinyl palmitate hydrolysis readout can identify novel genes regulating this activity.
How CRISPR Can Be Used to Study GO:0050253 retinyl-palmitate esterase activity
Knockout
CRISPR knockout of candidate genes (e.g., LIPE, PNPLA2) in liver or retinal cell lines can determine whether they are required for retinyl-palmitate esterase activity. Loss of activity would confirm a causal role.
Point Mutation
Introducing specific point mutations (e.g., catalytic serine to alanine) via CRISPR can dissect the enzymatic mechanism and identify critical residues for hydrolysis.
Knock-in
Knock-in of epitope tags or fluorescent proteins at endogenous loci allows visualization and purification of the enzyme without affecting its regulation.
Overexpression
CRISPR activation or cDNA overexpression can increase enzyme levels to study kinetics, substrate specificity, and downstream effects on retinol signaling.
How EDITGENE Supports retinyl-palmitate esterase activity Research
Researchers studying retinyl-palmitate esterase activity-related genes often need to determine whether a candidate gene is causally involved in the hydrolysis of retinyl esters. EDITGENE provides a comprehensive suite of CRISPR services to enable such investigations with precision and reproducibility.
Contact EDITGENE today to design your custom CRISPR model for retinyl-palmitate esterase activity research.
Frequently Asked Questions About retinyl-palmitate esterase activity
What is retinyl-palmitate esterase activity?
It is the enzymatic activity that hydrolyzes retinyl palmitate into retinol and palmitate, as defined by GO:0050253.
What genes are involved in retinyl-palmitate esterase activity?
Candidate genes include LIPE, PNPLA2, CES1, and others, though the exact enzymes are still being characterized.
Which tissues express retinyl-palmitate esterase activity?
It is found in liver, retina, and other tissues.
How is retinyl-palmitate esterase activity regulated?
It is influenced by nutritional status, such as protein and vitamin A levels.
What diseases are associated with retinyl-palmitate esterase activity?
Vitamin A deficiency, retinal disorders, and liver disease may involve altered activity.
How can I measure retinyl-palmitate esterase activity?
Common methods include HPLC-based assays with retinyl palmitate as substrate.
What is the reaction catalyzed by GO:0050253?
Retinyl palmitate + H2O = retinol + palmitate + H+.
Is retinyl-palmitate esterase activity the same as cholesteryl ester hydrolase?
No, they are distinct but can be inhibited by similar compounds.
Can CRISPR be used to study retinyl-palmitate esterase activity?
Yes, knockout, knock-in, and overexpression models can dissect gene function.
Where can I find more information about GO:0050253?
QuickGO provides the official definition and synonyms.
Conclusion
Retinyl-palmitate esterase activity (GO:0050253) is a key molecular function in vitamin A metabolism, enabling the release of retinol from its storage ester. Its presence in liver and retina, regulation by nutritional status, and distinct properties from other hydrolases make it an important subject for research. Understanding its mechanism and regulation can shed light on vitamin A-related diseases and inform therapeutic strategies. CRISPR-based models offer powerful tools to dissect the genes and pathways involved.
References
- 1. Harrison EH et al.. 1979. Unusual properties of retinyl palmitate hydrolase activity in rat liver.. J Lipid Res 20(6):753-9 PMID: 490052
- 2. Blaner WS et al.. 1984. Rat liver retinyl palmitate hydrolase activity. Relationship to cholesteryl oleate and triolein hydrolase activities.. Biochim Biophys Acta 794(3):419-27 PMID: 6743673
- 3. Tsin AT et al.. 1986. Decreased hepatic retinyl palmitate hydrolase activity in protein-deficient rats.. Biochim Biophys Acta 878(1):20-4 PMID: 3730411
- 4. Tsin AT et al.. 1986. Retinyl palmitate hydrolase activity in the bovine retina.. Biochem Biophys Res Commun 134(3):1209-14 PMID: 3947364
- 5. Mourey MS et al.. 1992. Retinyl palmitate hydrolase activity in human liver.. Am J Clin Nutr 55(3):729-33 PMID: 1550049
- 6. Blaner WS et al.. 1984. Inhibition of rat liver retinyl palmitate hydrolase activity by ether analogs of cholesteryl esters and acylglycerides.. Biochim Biophys Acta 794(3):428-34 PMID: 6743674
- 7. Blaner WS et al.. 1985. Spatial distribution of retinol-binding protein and retinyl palmitate hydrolase activity in normal and vitamin A-deficient rat liver.. J Nutr 115(7):856-64 PMID: 4040159
- 8. Unknown. 1982. Retinyl palmitate hydrolase activity of rat liver.. Nutr Rev 40(9):279-80 PMID: 7177501
