Retinyl phosphate

In the synthesis of most glycoproteins containing mannose, the intermediate carrier of the mannosyl moiety is the polyene dolichol phosphate. However, in some systems, retinyl phosphate can act as the intermediate carrier between UDP-mannose and the acceptor glycoprotein. Retinyl phosphate maimose seems to be involved especially in the synthesis of hydrophobic regions of glycoproteins (DeLuca, 1977 Frot-Coutaz et al., 1985). 

High Performance Liquid Chromatography.—This technique has been applied to a wide range of natural products, i.e., steroidal phosphates, retinyl phosphate, dansylated protein hydrolysates, thiamine phosphates, dibutyl c-AMP esters, cytosine arabinoside triphosphate, and di- and tri-nucleoside phosphates. ... 

In addition to glycosyl derivations of the dolichol phosphates, a family of somewhat similar compounds based on retinol has been described. Their biological role is still unclear, but they do not appear to be exact substitutes for their dolichol counterparts and in some cases no such equivalents are known. In general, cells contain much less retinol than dolichol, but only a small part of their dolichol can be involved in glycosyl transfers, so this is not indicative of an unimportant function for glycosyl retinyl phosphates. At the same time, until their purpose is more clearly defined, some care must be taken in ensuring that they are not artefacts that result from the addition of retinol to cell-free systems. 

Frot-Coutaz, Silverman-Jones and De Luca (1976) confirmed that retinol could be converted into retinyl phosphate by intact cells. Hamster intestinal epithelium was used and the product was characterised by a variety of partition and ion-exchange chromatographic procedures and by chemical comparison with an authentic (synthetic) sample of retinyl phosphate. Hence all the steps necessary for the synthesis of retinyl mannosyl phosphate from retinol could be demonstrated in the whole cell. 

What is the physiological role — if any — of retinyl mannosyl phosphate Does it act as a mannosyl donor in glycopeptide assembly There is no simple answer as yet. It is clearly established that many cells can synthesise retinyl phosphate from retinol and, thence, can produce retinyl mannosyl phosphate, so the substance itself is clearly a physiological product. 

Frot-Coutaz, J.P., Silverman-Jones, C.S. De Luca, L.M. (1976) Isolation, Characterisation and Biological Activity of Retinyl Phosphate from Hamster Intestinal Epithelium ,... 

Peterson, P.A., Rask, L., Helting, T., Ostberg, L. Femstedt, Y. (1976) Formation and Properties of Retinyl Phosphate Galactose , Journal of Biological Chemistry, 251,... 

Rosso, G., DeLuca, L., Warren, C.D. Wolf, G. (1975) Enzymatic Synthesis of Mannosyl Retinyl Phosphate from Retinyl Phosphate and Guanosine Diphosphate Mannose , Journal of Lipid Research, 16, 235-43... 

Rosso, G.C., Masushige, S., Quill, H. Wolf, G. (1977) Transfer of Mannose from Mannosyl Retinyl Phosphate to Protein , Proceedings of the National Academy of Sciences, USA, 74, 3762-6... 

Rosso, G.C., Masushige, S., Warren, C.D., Kiorpes, T. Wolf, G. (1976) The Anomeric Configuration of the D-Mannosyl Retinyl Phosphate Formed in Rat Liver Microsomes , Journal of Biological Chemistry, 251, 6465-7 Rubery, P.H. Northcote, D.H. (1970) The Effect of Auxin (2,4-dichloro-phenoxyacetic Acid) on the Synthesis of Cell Wall Polysaccharides in Cultured Sycamore Cells , Biochimica et Biophysica Acta, 222, 95-108... 

DeLuca, L. M., Brugh, M., and Silverman-Jones, C. S., 1984, Retinyl palmitate, retinyl phosphate, and dolichyl phosphate of postnuclear membrane fraction from hepatoma, host liver, and regenerating liver Marginal vitamin A status of hepatoma tissue. Cancer Res. 44 224. 

To synthesize retinyl phosphate (Poznyakov and Dmitrovshii, 1980), retinol (1) was reacted with either phosphoryl chloride or bis(triethylammonium) phosphate (Frot-Coutaz et al., 1981 Tsukida and Saiki, 1982). Treatment of the resulting product with cyclohexylamine in a final step led to the ammonium salt (600), which appears to be more stable toward alkaline hydrolysis than has been stated in previous reports. Photoisomerization of (600) gave the corresponding 13Z compound. 

It has been demonstrated that mammalian tissues synthesize retinyl phosphate. This was shown by incorporation of retinol-into this compound, using epithelial cells from hamster small intestine (Frot-Coutaz et al., 1976). Tritiated... 

Retinyl phosphate fxPorasil Gradient n-hexane - Kurokawa and... 

A radioimmunoassay method has been developed for the measurement of retinol and its derivatives in plasma (Conrad and Wirtz, 1973 Westfall and Wirtz, 1980 Wirtz and Westfall, 1981). Antibodies to retinoids are produced by injecting a conjugate of retinoic acid and albumin into rabbits. The antisera produced reacted well (K = 2 x 10 L/M) with a -trans-rttinoic acid, reti-naldehyde, retinol, and retinyl phosphate, less well with cis isomers, and poorly with retinyl palmitate, 3-carotene, and aromatic retinoids. As little as 1-2 ng of retinol could be detected in serum by this procedure. 

A13 Retinyl mannosyl hydrogen phosphate [61152-15-6] Mannosyl retinyl phosphate Retinyl p-D-mannopyranosyl hydrogen phosphate... 

Another set of reactions involving retinol that has been studied in liver concerns the formation of retinyl phosphate and of retinyl phosphomannose conjugates. These studies have been directed toward the hypothesis that retinoid-containing glycolipids serve as intermediates for specific glycosylation reactions. It is well established that the biosynthesis of some glycoproteins is markedly decreased in a number of tissues in retinoid deficiency, and that glycoprotein... 

Retinyl phosphate has been shown to be formed in mammalian cells both in vitro and in vivo and has been identified as a trace constitutent of certain mammalian membranes. Its glycosylated derivative mannosyl retinyl phosphate has also been shown to be formed both in vivo and in vitro. The enzyme system that forms mannosyl retinyl phosphate is located primarily in the rough endoplasmic reticulum of rat liver cells. Under appropriate conditions, glycosyl transfer can be demonstrated from the retinyl glycolipid to membrane glycoproteins. It is not known, however, whether this occurs in vivo under normal conditions. 

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