Vitamin A
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Basic Info
| Common Name | Vitamin A(F04735) |
| 2D Structure | |
| Description | Vitamin A (retinol) is a yellow fat-soluble, antioxidant vitamin important in vision and bone growth. It belongs to the family of chemical compounds known as retinoids. Retinol is ingested in a precursor form; animal sources (milk and eggs) contain retinyl esters, whereas plants (carrots, spinach) contain pro-vitamin A carotenoids. Hydrolysis of retinyl esters results in retinol while pro-vitamin A carotenoids can be cleaved to produce retinal. Retinal, also known as retinaldehyde, can be reversibly reduced to produce retinol or it can be irreversibly oxidized to produce retinoic acid. Retinol and derivatives of retinol that play an essential role in metabolic functioning of the retina, the growth of and differentiation of epithelial tissue, the growth of bone, reproduction, and the immune response. Dietary vitamin A is derived from a variety of carotenoids found in plants. It is enriched in the liver, egg yolks, and the fat component of dairy products. |
| FRCD ID | F04735 |
| CAS Number | 68-26-8 |
| PubChem CID | 445354 |
| Formula | C20H30O |
| IUPAC Name | (2E,4E,6E,8E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohexen-1-yl)nona-2,4,6,8-tetraen-1-ol |
| InChI Key | FPIPGXGPPPQFEQ-OVSJKPMPSA-N |
| InChI | InChI=1S/C20H30O/c1-16(8-6-9-17(2)13-15-21)11-12-19-18(3)10-7-14-20(19,4)5/h6,8-9,11-13,21H,7,10,14-15H2,1-5H3/b9-6+,12-11+,16-8+,17-13+ |
| Canonical SMILES | CC1=C(C(CCC1)(C)C)C=CC(=CC=CC(=CCO)C)C |
| Isomeric SMILES | CC1=C(C(CCC1)(C)C)/C=C/C(=C/C=C/C(=C/CO)/C)/C |
| Wikipedia | Vitamin A |
| Synonyms |
retinol
Oleovitamin A
Vitamin A
all-trans-Retinol
Vitamin A1
68-26-8
Alphalin
Axerophthol
Chocola A
Alphasterol
|
| Classifies |
Predicted: Veterinary Drug
|
| Update Date | Nov 13, 2018 17:07 |
Chemical Taxonomy
| Kingdom | Organic compounds |
| Superclass | Lipids and lipid-like molecules |
| Class | Prenol lipids |
| Subclass | Retinoids |
| Intermediate Tree Nodes | Not available |
| Direct Parent | Retinoids |
| Alternative Parents | |
| Molecular Framework | Aliphatic homomonocyclic compounds |
| Substituents | Retinoid skeleton - Diterpenoid - Fatty alcohol - Fatty acyl - Organic oxygen compound - Hydrocarbon derivative - Primary alcohol - Organooxygen compound - Alcohol - Aliphatic homomonocyclic compound |
| Description | This compound belongs to the class of organic compounds known as retinoids. These are oxygenated derivatives of 3,7-dimethyl-1-(2,6,6-trimethylcyclohex-1-enyl)nona-1,3,5,7-tetraene and derivatives thereof. |
Properties
| Property Name | Property Value |
|---|---|
| Molecular Weight | 286.459 |
| Hydrogen Bond Donor Count | 1 |
| Hydrogen Bond Acceptor Count | 1 |
| Rotatable Bond Count | 5 |
| Complexity | 496 |
| Monoisotopic Mass | 286.23 |
| Exact Mass | 286.23 |
| XLogP | 5.7 |
| Formal Charge | 0 |
| Heavy Atom Count | 21 |
| Defined Atom Stereocenter Count | 0 |
| Undefined Atom Stereocenter Count | 0 |
| Defined Bond Stereocenter Count | 4 |
| Undefined Bond Stereocenter Count | 0 |
| Isotope Atom Count | 0 |
| Covalently-Bonded Unit Count | 1 |
ADMET
| Model | Result | Probability |
|---|---|---|
| Absorption | ||
| Blood-Brain Barrier | BBB+ | 0.9665 |
| Human Intestinal Absorption | HIA+ | 0.9938 |
| Caco-2 Permeability | Caco2+ | 0.7272 |
| P-glycoprotein Substrate | Non-substrate | 0.5939 |
| P-glycoprotein Inhibitor | Non-inhibitor | 0.8205 |
| Non-inhibitor | 0.5631 | |
| Renal Organic Cation Transporter | Non-inhibitor | 0.7646 |
| Distribution | ||
| Subcellular localization | Lysosome | 0.8110 |
| Metabolism | ||
| CYP450 2C9 Substrate | Non-substrate | 0.8193 |
| CYP450 2D6 Substrate | Non-substrate | 0.8324 |
| CYP450 3A4 Substrate | Substrate | 0.5522 |
| CYP450 1A2 Inhibitor | Non-inhibitor | 0.9045 |
| CYP450 2C9 Inhibitor | Non-inhibitor | 0.9070 |
| CYP450 2D6 Inhibitor | Non-inhibitor | 0.9230 |
| CYP450 2C19 Inhibitor | Non-inhibitor | 0.9026 |
| CYP450 3A4 Inhibitor | Non-inhibitor | 0.8420 |
| CYP Inhibitory Promiscuity | Low CYP Inhibitory Promiscuity | 0.7388 |
| Excretion | ||
| Toxicity | ||
| Human Ether-a-go-go-Related Gene Inhibition | Weak inhibitor | 0.8563 |
| Non-inhibitor | 0.8853 | |
| AMES Toxicity | AMES toxic | 0.6952 |
| Carcinogens | Non-carcinogens | 0.7004 |
| Fish Toxicity | High FHMT | 0.8649 |
| Tetrahymena Pyriformis Toxicity | High TPT | 0.9884 |
| Honey Bee Toxicity | High HBT | 0.8263 |
| Biodegradation | Ready biodegradable | 0.5504 |
| Acute Oral Toxicity | III | 0.8739 |
| Carcinogenicity (Three-class) | Non-required | 0.6196 |
| Model | Value | Unit |
|---|---|---|
| Absorption | ||
| Aqueous solubility | -2.8144 | LogS |
| Caco-2 Permeability | 1.6607 | LogPapp, cm/s |
| Distribution | ||
| Metabolism | ||
| Excretion | ||
| Toxicity | ||
| Rat Acute Toxicity | 2.1249 | LD50, mol/kg |
| Fish Toxicity | 0.5928 | pLC50, mg/L |
| Tetrahymena Pyriformis Toxicity | 0.9025 | pIGC50, ug/L |
References
| Title | Journal | Date | Pubmed ID |
|---|---|---|---|
| Effects of methylmercury and retinol palmitate co-administration in rats during pregnancy and breastfeeding: Metabolic and redox parameters in dams and their offspring. | Ecotoxicol Environ Saf | 2018 Oct 30 | 30031321 |
| Vitamin A and D intake in pregnancy, infant supplementation, and asthma development: the Norwegian Mother and Child Cohort. | Am J Clin Nutr | 2018 May 1 | 29722838 |
| Vitamin A Deficiency Induces Autistic-Like Behaviors in Rats by Regulating theRARβ-CD38-Oxytocin Axis in the Hypothalamus. | Mol Nutr Food Res | 2018 Mar | 29266770 |
| Development of self-microemulsifying drug delivery system for oral delivery ofpoorly water-soluble nutraceuticals. | Drug Dev Ind Pharm | 2018 Jun | 29254385 |
| The bioavailability of iron, zinc, protein and vitamin A is highly variable inFrench individual diets: Impact on nutrient inadequacy assessment and relationwith the animal-to-plant ratio of diets. | Food Chem | 2018 Jan 1 | 28867104 |
| Food synergies for improving bioavailability of micronutrients from plant foods. | Food Chem | 2018 Jan 1 | 28867091 |
| Storage conditions and packaging greatly affects the stability of fortified wheatflour: Influence on vitamin A, iron, zinc, and oxidation. | Food Chem | 2018 Feb 1 | 28946293 |
| Effects of Pro-Oxidants and Antioxidants on the Total Antioxidant Capacity andLipid Oxidation Products of Milk During Refrigerated Storage. | J Food Sci | 2018 Feb | 29243810 |
| A simple and robust quantitative analysis of retinol and retinyl palmitate using a liquid chromatographic isocratic method. | J Food Drug Anal | 2018 Apr | 29567219 |
| Liver toxicity related to herbs and dietary supplements: Online table of case reports. Part 2 of 5 series. | Food Chem Toxicol | 2017 Sep | 27402097 |
| Dietary verbascoside supplementation in donkeys: effects on milk fatty acidprofile during lactation, and serum biochemical parameters and oxidative markers. | Animal | 2017 Sep | 28264745 |
| Rennet-induced coagulation of raw and heated camel and cow milk gels determinedby instrumental techniques: effects of added calcium and phosphate. | J Sci Food Agric | 2017 Sep | 28188640 |
| Are Low Intakes and Deficiencies in Iron, Vitamin A, Zinc, and Iodine of PublicHealth Concern in Ethiopian, Kenyan, Nigerian, and South African Children andAdolescents? | Food Nutr Bull | 2017 Sep | 28682645 |
| Micronutrient Status and Dietary Intake of Iron, Vitamin A, Iodine, Folate andZinc in Women of Reproductive Age and Pregnant Women in Ethiopia, Kenya, Nigeria and South Africa: A Systematic Review of Data from 2005 to 2015. | Nutrients | 2017 Oct 5 | 28981457 |
| Transcription factor ISX mediates the cross talk between diet and immunity. | Proc Natl Acad Sci U S A | 2017 Oct 24 | 29073082 |
| Polyunsaturated lipids and vitamin A oxidation during cod liver oil in vitro gastrointestinal digestion. Antioxidant effect of added BHT. | Food Chem | 2017 Oct 1 | 28490135 |
| The effect of bleaching agents on the degradation of vitamins and carotenoids in spray-dried whey protein concentrate. | J Dairy Sci | 2017 Oct | 28780108 |
| Provitamin A carotenoids from an engineered high-carotenoid maize arebioavailable and zeaxanthin does not compromise β-carotene absorption in poultry. | Transgenic Res | 2017 Oct | 28646243 |
| Iron, zinc, vitamin A and selenium status in a cohort of Indonesian infants afteradjusting for inflammation using several different approaches. | Br J Nutr | 2017 Nov | 29189196 |
| Counter-intuitive plasma vitamin D and zinc status in HIV-1-infected adults with persistent low-level viraemia after treatment initiation: a pilot case-controlstudy. | Eur J Clin Microbiol Infect Dis | 2017 Nov | 28647858 |
Targets
- General Function:
- Retinol dehydrogenase activity
- Specific Function:
- Stereospecific 11-cis retinol dehydrogenase, which catalyzes the final step in the biosynthesis of 11-cis retinaldehyde, the universal chromophore of visual pigments. Also able to oxidize 9-cis-retinol and 13-cis-retinol, but not all-trans-retinol. Active in the presence of NAD as cofactor but not in the presence of NADP.
- Gene Name:
- RDH5
- Uniprot ID:
- Q92781
- Molecular Weight:
- 34978.425 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Zhang M, Hu P, Krois CR, Kane MA, Napoli JL: Altered vitamin A homeostasis and increased size and adiposity in the rdh1-null mouse. FASEB J. 2007 Sep;21(11):2886-96. Epub 2007 Apr 13. [17435174 ]
- General Function:
- Zinc ion binding
- Specific Function:
- Nuclear receptor that binds and is activated by variety of endogenous and xenobiotic compounds. Transcription factor that activates the transcription of multiple genes involved in the metabolism and secretion of potentially harmful xenobiotics, drugs and endogenous compounds. Activated by the antibiotic rifampicin and various plant metabolites, such as hyperforin, guggulipid, colupulone, and isoflavones. Response to specific ligands is species-specific. Activated by naturally occurring steroids, such as pregnenolone and progesterone. Binds to a response element in the promoters of the CYP3A4 and ABCB1/MDR1 genes.
- Gene Name:
- NR1I2
- Uniprot ID:
- O75469
- Molecular Weight:
- 49761.245 Da
References
- Sipes NS, Martin MT, Kothiya P, Reif DM, Judson RS, Richard AM, Houck KA, Dix DJ, Kavlock RJ, Knudsen TB: Profiling 976 ToxCast chemicals across 331 enzymatic and receptor signaling assays. Chem Res Toxicol. 2013 Jun 17;26(6):878-95. doi: 10.1021/tx400021f. Epub 2013 May 16. [23611293 ]
- General Function:
- Retinal dehydrogenase activity
- Specific Function:
- Recognizes as substrates free retinal and cellular retinol-binding protein-bound retinal. Does metabolize octanal and decanal but does not metabolize citral, benzaldehyde, acetaldehyde and propanal efficiently (By similarity).
- Gene Name:
- ALDH1A2
- Uniprot ID:
- O94788
- Molecular Weight:
- 56723.495 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Isken A, Holzschuh J, Lampert JM, Fischer L, Oberhauser V, Palczewski K, von Lintig J: Sequestration of retinyl esters is essential for retinoid signaling in the zebrafish embryo. J Biol Chem. 2007 Jan 12;282(2):1144-51. Epub 2006 Nov 10. [17098734 ]
- General Function:
- Retinol dehydrogenase activity
- Specific Function:
- Retinol dehydrogenase with a clear preference for NADP. Converts all-trans-retinal to all-trans-retinol. May play a role in the regeneration of visual pigment at high light intensity (By similarity).
- Gene Name:
- RDH8
- Uniprot ID:
- Q9NYR8
- Molecular Weight:
- 33755.02 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Overington JP, Al-Lazikani B, Hopkins AL: How many drug targets are there? Nat Rev Drug Discov. 2006 Dec;5(12):993-6. [17139284 ]
- General Function:
- Transporter activity
- Specific Function:
- Intracellular transport of retinol.
- Gene Name:
- RBP1
- Uniprot ID:
- P09455
- Molecular Weight:
- 15850.13 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Yapi HF, Ahiboh H, Ago K, Ake M, Monnet D: [Protein profile and vitamin A in children of school age in Ivory Coast]. Ann Biol Clin (Paris). 2005 May-Jun;63(3):291-5. [15951260 ]
- General Function:
- Retinol dehydrogenase activity
- Specific Function:
- Catalyzes the reduction of all-trans-retinal to all-trans-retinol in the presence of NADPH.
- Gene Name:
- DHRS3
- Uniprot ID:
- O75911
- Molecular Weight:
- 33548.115 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Overington JP, Al-Lazikani B, Hopkins AL: How many drug targets are there? Nat Rev Drug Discov. 2006 Dec;5(12):993-6. [17139284 ]
- General Function:
- Thyroid hormone binding
- Specific Function:
- Recognizes as substrates free retinal and cellular retinol-binding protein-bound retinal. Seems to be the key enzyme in the formation of an RA gradient along the dorso-ventral axis during the early eye development and also in the development of the olfactory system (By similarity).
- Gene Name:
- ALDH1A3
- Uniprot ID:
- P47895
- Molecular Weight:
- 56107.995 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Halilagic A, Ribes V, Ghyselinck NB, Zile MH, Dolle P, Studer M: Retinoids control anterior and dorsal properties in the developing forebrain. Dev Biol. 2007 Mar 1;303(1):362-75. Epub 2006 Nov 17. [17184764 ]
- General Function:
- Transporter activity
- Specific Function:
- Soluble retinoid carrier essential the proper function of both rod and cone photoreceptors. Participates in the regeneration of active 11-cis-retinol and 11-cis-retinaldehyde, from the inactive 11-trans products of the rhodopsin photocycle and in the de novo synthesis of these retinoids from 11-trans metabolic precursors. The cycling of retinoids between photoreceptor and adjacent pigment epithelium cells is known as the 'visual cycle'.
- Gene Name:
- RLBP1
- Uniprot ID:
- P12271
- Molecular Weight:
- 36474.02 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Salvador-Silva M, Ghosh S, Bertazolli-Filho R, Boatright JH, Nickerson JM, Garwin GG, Saari JC, Coca-Prados M: Retinoid processing proteins in the ocular ciliary epithelium. Mol Vis. 2005 May 18;11:356-65. [15928609 ]
- General Function:
- Retinol dehydrogenase activity
- Specific Function:
- Exhibits an oxidoreductive catalytic activity towards retinoids. Most efficient as an NADPH-dependent retinal reductase. Displays high activity toward 9-cis and all-trans-retinol. Also involved in the metabolism of short-chain aldehydes. No steroid dehydrogenase activity detected. Might be the key enzyme in the formation of 11-cis-retinal from 11-cis-retinol during regeneration of the cone visual pigments.
- Gene Name:
- RDH12
- Uniprot ID:
- Q96NR8
- Molecular Weight:
- 35093.455 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Keller B, Adamski J: RDH12, a retinol dehydrogenase causing Leber's congenital amaurosis, is also involved in steroid metabolism. J Steroid Biochem Mol Biol. 2007 May;104(3-5):190-4. Epub 2007 Mar 23. [17512723 ]
- General Function:
- Transferase activity, transferring acyl groups
- Specific Function:
- Transfers the acyl group from the sn-1 position of phosphatidylcholine to all-trans retinol, producing all-trans retinyl esters. Retinyl esters are storage forms of vitamin A. LRAT plays a critical role in vision. It provides the all-trans retinyl ester substrates for the isomerohydrolase which processes the esters into 11-cis-retinol in the retinal pigment epithelium; due to a membrane-associated alcohol dehydrogenase, 11 cis-retinol is oxidized and converted into 11-cis-retinaldehyde which is the chromophore for rhodopsin and the cone photopigments.
- Gene Name:
- LRAT
- Uniprot ID:
- O95237
- Molecular Weight:
- 25702.635 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Kaschula CH, Jin MH, Desmond-Smith NS, Travis GH: Acyl CoA:retinol acyltransferase (ARAT) activity is present in bovine retinal pigment epithelium. Exp Eye Res. 2006 Jan;82(1):111-21. Epub 2005 Jul 27. [16054134 ]
- General Function:
- Alcohol dehydrogenase (nadp+) activity
- Specific Function:
- Exhibits an oxidoreductive catalytic activity towards retinoids. Most efficient as an NADPH-dependent retinal reductase. Displays high activity toward 9-cis and all-trans-retinol. No steroid dehydrogenase activity detected.
- Gene Name:
- RDH14
- Uniprot ID:
- Q9HBH5
- Molecular Weight:
- 36864.355 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Overington JP, Al-Lazikani B, Hopkins AL: How many drug targets are there? Nat Rev Drug Discov. 2006 Dec;5(12):993-6. [17139284 ]
- General Function:
- Zinc ion binding
- Specific Function:
- Receptor for retinoic acid. Retinoic acid receptors bind as heterodimers to their target response elements in response to their ligands, all-trans or 9-cis retinoic acid, and regulate gene expression in various biological processes. The RAR/RXR heterodimers bind to the retinoic acid response elements (RARE) composed of tandem 5'-AGGTCA-3' sites known as DR1-DR5 (By similarity). Specifically binds 9-cis retinoic acid (9C-RA).
- Gene Name:
- RXRB
- Uniprot ID:
- P28702
- Molecular Weight:
- 56921.38 Da
References
- Sipes NS, Martin MT, Kothiya P, Reif DM, Judson RS, Richard AM, Houck KA, Dix DJ, Kavlock RJ, Knudsen TB: Profiling 976 ToxCast chemicals across 331 enzymatic and receptor signaling assays. Chem Res Toxicol. 2013 Jun 17;26(6):878-95. doi: 10.1021/tx400021f. Epub 2013 May 16. [23611293 ]
- General Function:
- Lipid transporter activity
- Specific Function:
- APOD occurs in the macromolecular complex with lecithin-cholesterol acyltransferase. It is probably involved in the transport and binding of bilin. Appears to be able to transport a variety of ligands in a number of different contexts.
- Gene Name:
- APOD
- Uniprot ID:
- P05090
- Molecular Weight:
- 21275.37 Da
References
- Breustedt DA, Schonfeld DL, Skerra A: Comparative ligand-binding analysis of ten human lipocalins. Biochim Biophys Acta. 2006 Feb;1764(2):161-73. Epub 2006 Jan 6. [16461020 ]
- Specific Function:
- Keratin-binding protein required for epithelial cell polarization. Involved in apical junction complex (AJC) assembly via its interaction with PARD3. Required for ciliogenesis.
- Gene Name:
- FBF1
- Uniprot ID:
- Q8TES7
- Molecular Weight:
- 125445.19 Da
References
- N'soukpoe-Kossi CN, Sedaghat-Herati R, Ragi C, Hotchandani S, Tajmir-Riahi HA: Retinol and retinoic acid bind human serum albumin: stability and structural features. Int J Biol Macromol. 2007 Apr 10;40(5):484-90. Epub 2006 Nov 24. [17184834 ]
- General Function:
- Transporter activity
- Specific Function:
- Catalyzes the conversion of PGH2 to PGD2, a prostaglandin involved in smooth muscle contraction/relaxation and a potent inhibitor of platelet aggregation. Involved in a variety of CNS functions, such as sedation, NREM sleep and PGE2-induced allodynia, and may have an anti-apoptotic role in oligodendrocytes. Binds small non-substrate lipophilic molecules, including biliverdin, bilirubin, retinal, retinoic acid and thyroid hormone, and may act as a scavenger for harmful hydrophopic molecules and as a secretory retinoid and thyroid hormone transporter. Possibly involved in development and maintenance of the blood-brain, blood-retina, blood-aqueous humor and blood-testis barrier. It is likely to play important roles in both maturation and maintenance of the central nervous system and male reproductive system.
- Gene Name:
- PTGDS
- Uniprot ID:
- P41222
- Molecular Weight:
- 21028.665 Da
References
- Breustedt DA, Schonfeld DL, Skerra A: Comparative ligand-binding analysis of ten human lipocalins. Biochim Biophys Acta. 2006 Feb;1764(2):161-73. Epub 2006 Jan 6. [16461020 ]
- General Function:
- Retinol dehydrogenase activity
- Specific Function:
- Exhibits an oxidoreductive catalytic activity towards retinoids. Most efficient as an NADPH-dependent retinal reductase. Displays high activity towards 9-cis and all-trans-retinol. Also involved in the metabolism of short-chain aldehydes. No steroid dehydrogenase activity detected.
- Gene Name:
- RDH11
- Uniprot ID:
- Q8TC12
- Molecular Weight:
- 35385.955 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Gallego O, Belyaeva OV, Porte S, Ruiz FX, Stetsenko AV, Shabrova EV, Kostereva NV, Farres J, Pares X, Kedishvili NY: Comparative functional analysis of human medium-chain dehydrogenases, short-chain dehydrogenases/reductases and aldo-keto reductases with retinoids. Biochem J. 2006 Oct 1;399(1):101-9. [16787387 ]
- General Function:
- Transporter activity
- Specific Function:
- Intracellular transport of retinol.
- Gene Name:
- RBP2
- Uniprot ID:
- P50120
- Molecular Weight:
- 15706.595 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Suruga K, Kitagawa M, Yasutake H, Takase S, Goda T: Diet-related variation in cellular retinol-binding protein type II gene expression in rat jejunum. Br J Nutr. 2005 Dec;94(6):890-5. [16351764 ]
- General Function:
- Transporter activity
- Specific Function:
- Intracellular transport of retinol.
- Gene Name:
- RBP5
- Uniprot ID:
- P82980
- Molecular Weight:
- 15931.17 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- O'Byrne SM, Wongsiriroj N, Libien J, Vogel S, Goldberg IJ, Baehr W, Palczewski K, Blaner WS: Retinoid absorption and storage is impaired in mice lacking lecithin:retinol acyltransferase (LRAT). J Biol Chem. 2005 Oct 21;280(42):35647-57. Epub 2005 Aug 22. [16115871 ]
- Uniprot ID:
- P22932
References
- Sipes NS, Martin MT, Kothiya P, Reif DM, Judson RS, Richard AM, Houck KA, Dix DJ, Kavlock RJ, Knudsen TB: Profiling 976 ToxCast chemicals across 331 enzymatic and receptor signaling assays. Chem Res Toxicol. 2013 Jun 17;26(6):878-95. doi: 10.1021/tx400021f. Epub 2013 May 16. [23611293 ]
- General Function:
- Oxygen binding
- Specific Function:
- Catalyzes the formation of aromatic C18 estrogens from C19 androgens.
- Gene Name:
- CYP19A1
- Uniprot ID:
- P11511
- Molecular Weight:
- 57882.48 Da
References
- Sipes NS, Martin MT, Kothiya P, Reif DM, Judson RS, Richard AM, Houck KA, Dix DJ, Kavlock RJ, Knudsen TB: Profiling 976 ToxCast chemicals across 331 enzymatic and receptor signaling assays. Chem Res Toxicol. 2013 Jun 17;26(6):878-95. doi: 10.1021/tx400021f. Epub 2013 May 16. [23611293 ]
- General Function:
- Zinc ion binding
- Specific Function:
- Nuclear hormone receptor. Transcription factor that mediates the action of vitamin D3 by controlling the expression of hormone sensitive genes. Recruited to promoters via its interaction with BAZ1B/WSTF which mediates the interaction with acetylated histones, an essential step for VDR-promoter association. Plays a central role in calcium homeostasis.
- Gene Name:
- VDR
- Uniprot ID:
- P11473
- Molecular Weight:
- 48288.64 Da
References
- Sipes NS, Martin MT, Kothiya P, Reif DM, Judson RS, Richard AM, Houck KA, Dix DJ, Kavlock RJ, Knudsen TB: Profiling 976 ToxCast chemicals across 331 enzymatic and receptor signaling assays. Chem Res Toxicol. 2013 Jun 17;26(6):878-95. doi: 10.1021/tx400021f. Epub 2013 May 16. [23611293 ]
- General Function:
- Zinc ion binding
- Specific Function:
- Transcriptional regulator which is important for the differentiation and maintenance of meso-diencephalic dopaminergic (mdDA) neurons during development. It is crucial for expression of a set of genes such as SLC6A3, SLC18A2, TH and DRD2 which are essential for development of mdDA neurons (By similarity).
- Gene Name:
- NR4A2
- Uniprot ID:
- P43354
- Molecular Weight:
- 66590.375 Da
References
- Sipes NS, Martin MT, Kothiya P, Reif DM, Judson RS, Richard AM, Houck KA, Dix DJ, Kavlock RJ, Knudsen TB: Profiling 976 ToxCast chemicals across 331 enzymatic and receptor signaling assays. Chem Res Toxicol. 2013 Jun 17;26(6):878-95. doi: 10.1021/tx400021f. Epub 2013 May 16. [23611293 ]
- General Function:
- Retinol transporter activity
- Specific Function:
- Delivers retinol from the liver stores to the peripheral tissues. In plasma, the RBP-retinol complex interacts with transthyretin, this prevents its loss by filtration through the kidney glomeruli.
- Gene Name:
- RBP4
- Uniprot ID:
- P02753
- Molecular Weight:
- 23009.8 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Goodman AB: Retinoid receptors, transporters, and metabolizers as therapeutic targets in late onset Alzheimer disease. J Cell Physiol. 2006 Dec;209(3):598-603. [17001693 ]
- General Function:
- Retinal dehydrogenase activity
- Specific Function:
- Binds free retinal and cellular retinol-binding protein-bound retinal. Can convert/oxidize retinaldehyde to retinoic acid (By similarity).
- Gene Name:
- ALDH1A1
- Uniprot ID:
- P00352
- Molecular Weight:
- 54861.44 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Asson-Batres MA, Smith WB: Localization of retinaldehyde dehydrogenases and retinoid binding proteins to sustentacular cells, glia, Bowman's gland cells, and stroma: potential sites of retinoic acid synthesis in the postnatal rat olfactory organ. J Comp Neurol. 2006 May 10;496(2):149-71. [16538685 ]
- General Function:
- Serine-type peptidase activity
- Specific Function:
- IRBP shuttles 11-cis and all trans retinoids between the retinol isomerase in the pigment epithelium and the visual pigments in the photoreceptor cells of the retina.
- Gene Name:
- RBP3
- Uniprot ID:
- P10745
- Molecular Weight:
- 135361.46 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Qtaishat NM, Wiggert B, Pepperberg DR: Interphotoreceptor retinoid-binding protein (IRBP) promotes the release of all-trans retinol from the isolated retina following rhodopsin bleaching illumination. Exp Eye Res. 2005 Oct;81(4):455-63. Epub 2005 Jun 2. [15935345 ]
- General Function:
- Transporter activity
- Specific Function:
- Intracellular transport of retinol.
- Gene Name:
- RBP7
- Uniprot ID:
- Q96R05
- Molecular Weight:
- 15535.585 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Overington JP, Al-Lazikani B, Hopkins AL: How many drug targets are there? Nat Rev Drug Discov. 2006 Dec;5(12):993-6. [17139284 ]
- General Function:
- Oxidoreductase activity
- Specific Function:
- Retinol saturase carrying out the saturation of the 13-14 double bond of all-trans-retinol to produce all-trans-13,14-dihydroretinol. Has activity toward all-trans-retinol as substrate. Does not use all-trans-retinoic acid nor 9-cis, 11-cis or 13-cis-retinol isomers as substrates. May play a role in the metabolism of vitamin A (By similarity).
- Gene Name:
- RETSAT
- Uniprot ID:
- Q6NUM9
- Molecular Weight:
- 66818.935 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Moise AR, Isken A, Dominguez M, de Lera AR, von Lintig J, Palczewski K: Specificity of zebrafish retinol saturase: formation of all-trans-13,14-dihydroretinol and all-trans-7,8- dihydroretinol. Biochemistry. 2007 Feb 20;46(7):1811-20. Epub 2007 Jan 25. [17253779 ]
- General Function:
- Receptor binding
- Specific Function:
- Reduces all-trans-retinal and 9-cis retinal. Can also catalyze the oxidation of all-trans-retinol with NADP as co-factor, but with much lower efficiency. Reduces alkyl phenyl ketones and alpha-dicarbonyl compounds with aromatic rings, such as pyrimidine-4-aldehyde, 3-benzoylpyridine, 4-benzoylpyridine, menadione and 4-hexanoylpyridine. Has no activity towards aliphatic aldehydes and ketones (By similarity).
- Gene Name:
- DHRS4
- Uniprot ID:
- Q9BTZ2
- Molecular Weight:
- 29536.885 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Du K, Liu GF, Xie JP, Song XH, Li R, Liang B, Huang DY: A 27.368 kDa retinal reductase in New Zealand white rabbit liver cytosol encoded by the peroxisomal retinol dehydrogenase-reductase cDNA: purification and characterization of the enzyme. Biochem Cell Biol. 2007 Apr;85(2):209-17. [17534402 ]
- General Function:
- Oxidoreductase activity
- Specific Function:
- Does not exhibit retinol dehydrogenase (RDH) activity in vitro.
- Gene Name:
- RDH13
- Uniprot ID:
- Q8NBN7
- Molecular Weight:
- 35931.85 Da
- Mechanism of Action:
- Vision:Vitamin A (all-<i>trans</i> retinol) is converted in the retina to the 11-<i>cis</i>-isomer of retinaldehyde or 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-<i>cis</i>-retinal, while attached to opsin in rhodopsin is isomerized to all-<i>trans</i>-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-<i>trans</i>-retinal is then released from opsin and reduced to all-<i>trans</i>-retinol. All-<i>trans</i>-retinol is isomerized to 11-<i>cis</i>-retinol in the dark, and then oxidized to 11-<i>cis</i>-retinal. 11-<i>cis</i>-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-<i>cis</i> retinal rapidly. <br/>Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.
References
- Keller B, Adamski J: RDH12, a retinol dehydrogenase causing Leber's congenital amaurosis, is also involved in steroid metabolism. J Steroid Biochem Mol Biol. 2007 May;104(3-5):190-4. Epub 2007 Mar 23. [17512723 ]
- General Function:
- Zinc ion binding
- Specific Function:
- Receptor for retinoic acid. Retinoic acid receptors bind as heterodimers to their target response elements in response to their ligands, all-trans or 9-cis retinoic acid, and regulate gene expression in various biological processes. The RXR/RAR heterodimers bind to the retinoic acid response elements (RARE) composed of tandem 5'-AGGTCA-3' sites known as DR1-DR5. In the absence of ligand, the RXR-RAR heterodimers associate with a multiprotein complex containing transcription corepressors that induce histone acetylation, chromatin condensation and transcriptional suppression. On ligand binding, the corepressors dissociate from the receptors and associate with the coactivators leading to transcriptional activation. RARA plays an essential role in the regulation of retinoic acid-induced germ cell development during spermatogenesis. Has a role in the survival of early spermatocytes at the beginning prophase of meiosis. In Sertoli cells, may promote the survival and development of early meiotic prophase spermatocytes. In concert with RARG, required for skeletal growth, matrix homeostasis and growth plate function (By similarity). Regulates expression of target genes in a ligand-dependent manner by recruiting chromatin complexes containing KMT2E/MLL5. Mediates retinoic acid-induced granulopoiesis.
- Gene Name:
- RARA
- Uniprot ID:
- P10276
- Molecular Weight:
- 50770.805 Da
References
- Sipes NS, Martin MT, Kothiya P, Reif DM, Judson RS, Richard AM, Houck KA, Dix DJ, Kavlock RJ, Knudsen TB: Profiling 976 ToxCast chemicals across 331 enzymatic and receptor signaling assays. Chem Res Toxicol. 2013 Jun 17;26(6):878-95. doi: 10.1021/tx400021f. Epub 2013 May 16. [23611293 ]
- General Function:
- Zinc ion binding
- Specific Function:
- Nuclear hormone receptor. The steroid hormones and their receptors are involved in the regulation of eukaryotic gene expression and affect cellular proliferation and differentiation in target tissues. Ligand-dependent nuclear transactivation involves either direct homodimer binding to a palindromic estrogen response element (ERE) sequence or association with other DNA-binding transcription factors, such as AP-1/c-Jun, c-Fos, ATF-2, Sp1 and Sp3, to mediate ERE-independent signaling. Ligand binding induces a conformational change allowing subsequent or combinatorial association with multiprotein coactivator complexes through LXXLL motifs of their respective components. Mutual transrepression occurs between the estrogen receptor (ER) and NF-kappa-B in a cell-type specific manner. Decreases NF-kappa-B DNA-binding activity and inhibits NF-kappa-B-mediated transcription from the IL6 promoter and displace RELA/p65 and associated coregulators from the promoter. Recruited to the NF-kappa-B response element of the CCL2 and IL8 promoters and can displace CREBBP. Present with NF-kappa-B components RELA/p65 and NFKB1/p50 on ERE sequences. Can also act synergistically with NF-kappa-B to activate transcription involving respective recruitment adjacent response elements; the function involves CREBBP. Can activate the transcriptional activity of TFF1. Also mediates membrane-initiated estrogen signaling involving various kinase cascades. Isoform 3 is involved in activation of NOS3 and endothelial nitric oxide production. Isoforms lacking one or several functional domains are thought to modulate transcriptional activity by competitive ligand or DNA binding and/or heterodimerization with the full length receptor. Essential for MTA1-mediated transcriptional regulation of BRCA1 and BCAS3. Isoform 3 can bind to ERE and inhibit isoform 1.
- Gene Name:
- ESR1
- Uniprot ID:
- P03372
- Molecular Weight:
- 66215.45 Da
References
- Sipes NS, Martin MT, Kothiya P, Reif DM, Judson RS, Richard AM, Houck KA, Dix DJ, Kavlock RJ, Knudsen TB: Profiling 976 ToxCast chemicals across 331 enzymatic and receptor signaling assays. Chem Res Toxicol. 2013 Jun 17;26(6):878-95. doi: 10.1021/tx400021f. Epub 2013 May 16. [23611293 ]
- General Function:
- Zinc ion binding
- Specific Function:
- Receptor for retinoic acid. Retinoic acid receptors bind as heterodimers to their target response elements in response to their ligands, all-trans or 9-cis retinoic acid, and regulate gene expression in various biological processes. The RAR/RXR heterodimers bind to the retinoic acid response elements (RARE) composed of tandem 5'-AGGTCA-3' sites known as DR1-DR5. The high affinity ligand for RXRs is 9-cis retinoic acid. RXRA serves as a common heterodimeric partner for a number of nuclear receptors. The RXR/RAR heterodimers bind to the retinoic acid response elements (RARE) composed of tandem 5'-AGGTCA-3' sites known as DR1-DR5. In the absence of ligand, the RXR-RAR heterodimers associate with a multiprotein complex containing transcription corepressors that induce histone acetylation, chromatin condensation and transcriptional suppression. On ligand binding, the corepressors dissociate from the receptors and associate with the coactivators leading to transcriptional activation. The RXRA/PPARA heterodimer is required for PPARA transcriptional activity on fatty acid oxidation genes such as ACOX1 and the P450 system genes.
- Gene Name:
- RXRA
- Uniprot ID:
- P19793
- Molecular Weight:
- 50810.835 Da
References
- Sipes NS, Martin MT, Kothiya P, Reif DM, Judson RS, Richard AM, Houck KA, Dix DJ, Kavlock RJ, Knudsen TB: Profiling 976 ToxCast chemicals across 331 enzymatic and receptor signaling assays. Chem Res Toxicol. 2013 Jun 17;26(6):878-95. doi: 10.1021/tx400021f. Epub 2013 May 16. [23611293 ]