| LRAT | |||||||||||||||||||||||||||||||||||||||||||||||||||
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| Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Aliases | LRAT , LCA14, lecithin retinol acyltransferase (phosphatidylcholine--retinol O-acyltransferase), lecithin retinol acyltransferase | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 604863; MGI: 1891259; HomoloGene: 3483; GeneCards: LRAT; OMA:LRAT - orthologs | ||||||||||||||||||||||||||||||||||||||||||||||||||
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| Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Lecithin retinol acyltransferase is an enzyme that in humans is encoded by the LRAT gene. [5] [6]
Lecithin retinol acyltransferase is a microsomal enzyme that catalyzes the esterification of all-trans-retinol into all-trans-retinyl ester during phototransduction, an essential reaction for the retinoid cycle in visual system and vitamin A status in liver.
Mutations in this gene have been associated with early-onset severe retinal dystrophy. [6]
LRAT was overexpressed in colorectal cancer cells compared to normal colonic epithelium. Strong LRAT expression was associated with a poor prognosis in patients with colorectal cancer. [7]
Vitamin A is a fat-soluble vitamin that is an essential nutrient. The term "vitamin A" encompasses a group of chemically related organic compounds that includes retinol, retinyl esters, and several provitamin (precursor) carotenoids, most notably β-carotene (beta-carotene). Vitamin A has multiple functions: growth during embryo development, maintaining the immune system, and healthy vision. For aiding vision specifically, it combines with the protein opsin to form rhodopsin, the light-absorbing molecule necessary for both low-light and color vision.
Retinal is a polyene chromophore. Retinal, bound to proteins called opsins, is the chemical basis of visual phototransduction, the light-detection stage of visual perception (vision).
Guanylate cyclase 2C, also known as guanylyl cyclase C (GC-C), intestinal guanylate cyclase, guanylate cyclase-C receptor, or the heat-stable enterotoxin receptor (hSTAR) is an enzyme that in humans is encoded by the GUCY2C gene.
Carotenoid oxygenases are a family of enzymes involved in the cleavage of carotenoids to produce, for example, retinol, commonly known as vitamin A. This family includes an enzyme known as RPE65 which is abundantly expressed in the retinal pigment epithelium where it catalyzed the formation of 11-cis-retinol from all-trans-retinyl esters.
Lecithin–cholesterol acyltransferase is an enzyme found in many animals, including humans. It converts free cholesterol into cholesteryl ester, a more hydrophobic form of cholesterol. This process sequesters cholesterol ester into the core of a lipoprotein particle, eventually making the newly synthesized HDL spherical and forcing the reaction to become unidirectional since the particles are removed from the surface. The enzyme is bound to high-density lipoproteins (HDLs) (alpha-LCAT) and LDLs (beta-LCAT) in the blood plasma. LCAT deficiency can cause impaired vision due to cholesterol corneal opacities, anemia, and kidney damage. It belongs to the family of phospholipid:diacylglycerol acyltransferases.
Vitamin A receptor, Stimulated by retinoic acid 6 or STRA6 protein was originally discovered as a transmembrane cell-surface receptor for retinol-binding protein. STRA6 is unique as it functions both as a membrane transporter and a cell surface receptor, particularly as a cytokine receptor. In fact, STRA6 may be the first of a whole new class of proteins that might be known as "cytokine signaling transporters." STRA6 is primarily known as the receptor for retinol binding protein and for its relevance in the transport of retinol to specific sites such as the eye. It does this through the removal of retinol (ROH) from the holo-Retinol Binding Protein (RBP) and transports it into the cell to be metabolized into retinoids and/or kept as a retinylester. As a receptor, after holo-RBP is bound, STRA6 activates the JAK/STAT pathway, resulting in the activation of transcription factor, STAT5. These two functions—retinol transporter and cytokine receptor—while using different pathways, are processes that depend on each other.
The visual cycle is a process in the retina that replenishes the molecule retinal for its use in vision. Retinal is the chromophore of most visual opsins, meaning it captures the photons to begin the phototransduction cascade. When the photon is absorbed, the 11-cis retinal photoisomerizes into all-trans retinal as it is ejected from the opsin protein. Each molecule of retinal must travel from the photoreceptor cell to the RPE and back in order to be refreshed and combined with another opsin. This closed enzymatic pathway of 11-cis retinal is sometimes called Wald's visual cycle after George Wald (1906–1997), who received the Nobel Prize in 1967 for his work towards its discovery.
In enzymology, a retinol dehydrogenase (RDH) (EC 1.1.1.105) is an enzyme that catalyzes the chemical reaction
RPE-retinal G protein-coupled receptor also known as RGR-opsin is a protein that in humans is encoded by the RGR gene. RGR-opsin is a member of the rhodopsin-like receptor subfamily of GPCR. Like other opsins which bind retinaldehyde, it contains a conserved lysine residue in the seventh transmembrane domain. RGR-opsin comes in different isoforms produced by alternative splicing.
Retinal pigment epithelium-specific 65 kDa protein is a retinoid isomerohydrolase enzyme of the vertebrate visual cycle. RPE65 is expressed in the retinal pigment epithelium and is responsible for the conversion of all-trans-retinyl esters to 11-cis-retinol during phototransduction. 11-cis-retinol is then used in visual pigment regeneration in photoreceptor cells. RPE65 belongs to the carotenoid oxygenase family of enzymes.
Retinol binding protein 1, cellular, also known as RBP1, is a protein that in humans is encoded by the RBP1 gene.
11-cis retinol dehydrogenase is an enzyme that in humans is encoded by the RDH5 gene.
Retinol dehydrogenase 11 is an enzyme that in humans is encoded by the RDH11 gene.
Retinol-binding protein 2 (RBP2) is a protein that in humans is encoded by the RBP2 gene.
Aldo-keto reductase family 1 member B10 is an enzyme that in humans is encoded by the AKR1B10 gene.
Retinol dehydrogenase 12 is an enzyme that in humans is encoded by the RDH12 gene.
Retinol dehydrogenase 8 is an enzyme that in humans is encoded by the RDH8 gene.
CYP27C1 is a protein that in humans is encoded by the CYP27C1 gene. The Enzyme Commission number (EC) for this protein is EC 1.14.19.53. The full accepted name is all-trans-retinol 3,4-desaturase and the EC number 1 classifies CYP27C1 as a oxidoreductase that acts on paired donor by reducing oxygen. It is also identifiable by the UniProt code Q4G0S4.
1-Lysophosphatidylcholines are a class of phospholipids that are intermediates in the metabolism of lipids. They result from the hydrolysis of an acyl group from the sn-1 position of phosphatidylcholine. They are also called 2-acyl-sn-glycero-3-phosphocholines. The synthesis of phosphatidylcholines with specific fatty acids occurs through the synthesis of 1-lysoPC. The formation of various other lipids generates 1-lysoPC as a by-product.
Retinol dehydrogenase 13 (all-trans/9-cis) is a protein that in humans is encoded by the RDH13 gene. This gene encodes a mitochondrial short-chain dehydrogenase/reductase, which catalyzes the reduction and oxidation of retinoids. The encoded enzyme may function in retinoic acid production and may also protect the mitochondria against oxidative stress. Alternatively spliced transcript variants have been described.
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