Lecithin retinol acyltransferase

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Lecithin retinol acyltransferase
Properties of human protein
Mass / length primary structure 230 amino acids
Secondary to quaternary structure Membrane protein (ER)
Identifier
Gene name LRAT
External IDs
Enzyme classification
EC, category 2.3.1.135 ,  transferase
Response type Transfer of a fatty acid residue
Substrate 1,2-diacyl lecithin + retinol
Products 2-acyl lecithin + retinyl ester
Occurrence
Parent taxon Vertebrates

The lecithin retinol acyltransferase (LRAT) is the enzyme in vertebrates , comprising the esterification of retinol catalyzed . This reaction takes place in all tissue types that store vitamin A , but especially in the retina , liver and intestines . Retinyl esters (mainly retinyl palmitate in humans) are also the preferred form in which vitamin A is transported from the intestine to the liver. LRAT is located in the membrane of the ER and receives one of the two substrates from there. Mutations in the LRAT -Gen are a cause of retinitis pigmentosa .

Rats without LRAT are unable to form vesicles in liver Ito cells that serve as fat stores. The storage of vitamin A in the retina was investigated in mice and was dependent on the presence of LRAT. In many human cancer cell lines which gene expression of LRAT lowered. On the other hand, mice with increased LRAT expression are more sensitive to carcinogens in the oral area.

Catalyzed reaction

Retinol+ +Dipalmitoyl lecithin
Retinyl palmitate2-palmitoyl lecithin

All-trans retinol and dipalmitoyl lecithin are converted into retinyl palmitate and 2-palmitoyl lecithin.

Individual evidence

  1. ↑ Homologues at OMA
  2. ↑ UniProt O95237
  3. ↑ Moise AR, Golczak M, Imanishi Y, Palczewski K: Topology and membrane association of lecithin: retinol acyltransferase . In: J. Biol. Chem. . 282, No. 3, January 2007, pp. 2081-90. doi : 10.1074 / jbc.M608315200 . PMID 17114808 .
  4. ↑ Blaner WS, O'Byrne SM, Wongsiriroj N, et al. : Hepatic stellate cell lipid droplets: a specialized lipid droplet for retinoid storage . In: Biochim. Biophys. Acta . 1791, No. 6, June 2009, pp. 467-73. doi : 10.1016 / j.bbalip.2008.11.001 . PMID 19071229 . PMC 2719539 (free full text).
  5. ↑ Ruiz A, Ghyselinck NB, Mata N, et al. : Somatic ablation of the Lrat gene in the mouse retinal pigment epithelium drastically reduces its retinoid storage . In: Invest. Ophthalmol. Vis. Sci. . 48, No. 12, December 2007, pp. 5377-87. doi : 10.1167 / iovs.07-0673 . PMID 18055784 .
  6. ↑ Cai K, Gudas LJ: Retinoic acid receptors and GATA transcription factors activate the transcription of the human lecithin: retinol acyltransferase gene . In: Int. J. Biochem. Cell Biol . 41, No. 3, March 2009, pp. 546-53. doi : 10.1016 / j.biocel.2008.06.007 . PMID 18652909 . PMC 2628449 (free full text).
  7. ↑ Tang XH, Su D, Albert M, Scognamiglio T, Gudas LJ: Overexpression of lecithin: retinol acyltransferase in the epithelial basal layer makes mice more sensitive to oral cavity carcinogenesis induced by a carcinogen . In: Cancer Biol. Ther. . 8, No. 13, July 2009, pp. 1212-3. PMID 19471114 . PMC 2882701 (free full text).