retinol-phosphate and mannosylretinylphosphate

Topics: Absorption; Animals; beta Carotene; Biological Transport; Carotenoids; Cell Differentiation; Cell Membrane; Cell Nucleus; Chemical Phenomena; Chemistry; Diterpenes; Homeostasis; Humans; Intracellular Membranes; Polyisoprenyl Phosphate Monosaccharides; Terminology as Topic; Tretinoin; Vitamin A

Topics: Animals; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Cricetinae; Diterpenes; Dolichol Monophosphate Mannose; Guanosine Diphosphate; Intracellular Membranes; Liver; Mannose; Mannosyltransferases; Mesocricetus; Polyisoprenyl Phosphate Monosaccharides; Polyisoprenyl Phosphate Sugars; Rats; Vitamin A

Hamster liver microsomal membranes catalyse the synthesis of retinyl phosphate mannose (Ret-P-Man) from GDP-mannose and exogenous retinyl phosphate (Ret-P). We have previously shown that maximal Ret-P-Man synthesis occurs in vitro at 20-30 min, followed by a subsequent loss of mannose from Ret-P-Man, suggestive of an intermediary function of Ret-P-Man and/or Ret-P-Man breakdown [Shidoji, Silverman-Jones & De Luca (1982) Biochem. J. 208, 865-868; Creek, Morre, Silverman-Jones, Shidoji & De Luca (1983) Biochem. J. 210, 541-547). To monitor Ret-P-Man synthesis and breakdown carefully, we developed a chromatographic system in which mannose, Ret-P-Man, mannose phosphate and GDP-mannose are separated in a single analysis on a Mono Q column eluted with a gradient of NaCl. Using this chromatographic system, we have determined that 80-90% of the Ret-P-Man made in vitro by hamster liver membranes in 30 min is recovered with the membranes upon centrifugation. Subsequent incubation of Ret-P-Man-loaded membranes at 37 degrees C results in a non-enzymic breakdown of Ret-P-Man to beta-mannopyranosyl phosphate and anhydroretinol. However, incubation of the Ret-P-Man-loaded hamster liver membranes with GDP, but not GMP, ADP, CDP or UDP, results in a loss of mannose from Ret-P-Man and the formation of GDP-mannose and Ret-P. These results demonstrate that Ret-P-Man synthesized in vitro is subject to non-enzymic breakdown to beta-mannopyranosyl phosphate and anhydroretinol and that the GDP-mannose:retinyl phosphate mannosyltransferase reaction is reversible.

Topics: Animals; Cell Membrane; Chromatography, High Pressure Liquid; Cricetinae; Diterpenes; Guanosine Diphosphate Mannose; In Vitro Techniques; Kinetics; Male; Mesocricetus; Microsomes, Liver; Nucleotides; Polyisoprenyl Phosphate Monosaccharides; Polyisoprenyl Phosphate Sugars; Spectrophotometry; Vitamin A

The guanosine diphosphate and uridine diphosphate esters of the antiviral sugar analog 2-deoxy-2-fluoro-D-glucose (GDP-FGlc and UDP-FGlc) were synthesized and tested as inhibitors of formation of lipid-linked sugars in cell-free extracts. Formation of dolichol-phosphate mannose and of dolichol-diphosphate di-N-acetyl-chitobiose were not inhibited by either sugar nucleotide. Formation of dolichol-phosphate glucose was inhibited by UDP-FGlc, not by GDP-FGlc. Although GDP-FGlc did not inhibit formation of dolichol-phosphate mannose, it did inhibit formation of retinol-phosphate mannose from retinol-phosphate and GDP-Man. This inhibition was not reversed by exogenous retinol-phosphate, nor was FGlc from GDP-FGlc incorporated into retinol-phosphate-linked derivatives. As FGLc inhibits formation of dolichol-phosphate mannose in intact cells, but does not decrease pool sizes of GDP-Man and dolichol-phosphate (Datema et al., 1980, Eur. J. Biochem. 109, 331-341), we discuss that inhibition of formation of retinol-phosphate mannose by one of the metabolites of FGlc, namely GDP-FGlc, may lead to decreased synthesis of dolichol-phosphate mannose in FGlc-treated cells. This implies a role for vitamin A in the dolichol cycle of protein glycosylation.

Topics: Animals; Carbon Radioisotopes; Cell Transformation, Viral; Cells, Cultured; Chick Embryo; Deoxy Sugars; Deoxyglucose; Diterpenes; Guanosine Diphosphate Mannose; Kinetics; Microsomes, Liver; Orthomyxoviridae; Polyisoprenyl Phosphate Monosaccharides; Polyisoprenyl Phosphate Sugars; Rats; Vitamin A

Of the subcellular fractions of rat liver the endoplasmic reticulum was the most active in GDP-mannose: retinyl phosphate mannosyl-transfer activity. The synthesis of retinyl phosphate mannose reached a maximum at 20-30 min of incubation and declined at later times. Retinyl phosphate mannose and dolichyl phosphate mannose from endogenous retinyl phosphate and dolichyl phosphate could also be assayed in the endoplasmic reticulum. About 1.8 ng (5 pmol) of endogenous retinyl phosphate was mannosylated per mg of endoplasmic reticulum protein (15 min at 37 degrees C, in the presence of 5 mM-MnCl2), and about 0.15 ng (0.41 pmol) of endogenous retinyl phosphate was mannosylated with Golgi-apparatus membranes. About 20 ng (13.4 pmol) of endogenous dolichyl phosphate was mannosylated in endoplasmic reticulum and 4.5 ng (3 pmol) in Golgi apparatus under these conditions. Endoplasmic reticulum, but not Golgi-apparatus membranes, catalysed significant transfer of [14C]mannose to endogenous acceptor proteins in the presence of exogenous retinyl phosphate. Mannosylation of endogenous acceptors in the presence of exogenous dolichyl phosphate required the presence of Triton X-100 and could not be detected when dolichyl phosphate was solubilized in liposomes. Dolichyl phosphate mainly stimulated the incorporation of mannose into the lipid-oligosaccharide-containing fraction, whereas retinyl phosphate transferred mannose directly to protein.

Topics: Animals; Chlorides; Diterpenes; Dolichol Monophosphate Mannose; Dolichol Phosphates; Endoplasmic Reticulum; Golgi Apparatus; Guanosine Diphosphate Mannose; In Vitro Techniques; Kinetics; Lipopolysaccharides; Liver; Male; Manganese; Manganese Compounds; Nucleoside Diphosphate Sugars; Polyisoprenyl Phosphate Monosaccharides; Polyisoprenyl Phosphates; Rats; Vitamin A

Adult Brugia pahangi took up and incorporated beta-carotene and free retinol in vitro. The uptake of retinol was 50 times greater than that of beta-carotene under similar incubation conditions. beta-Carotene was almost entirely metabolized, primarily to retinol. The metabolism of retinol by B. pahangi in vitro was less extensive, with a variety of retinoids tentatively identified, including retinyl phosphate (Ret-P), retinyl phosphate mannose (Ret-P-Man) and anhydroretinol as minor metabolites. B. pahangi microsomes were also shown to biosynthesize Ret-P-Man from exogenous Ret-P and GDP-mannose, but not from endogenous lipid acceptors alone. In this circumstance an unidentified lipid appeared to be mannosylated by B. pahangi. The rate of mannose transfer to exogenous Ret-P by B. pahangi microsomes was 150 pmol X min -1. (mg of protein) -1. Ret-P-Man synthetase activity from both B. pahangi and rat liver microsomes had an absolute requirement for bovine serum albumin and MnCl2, and occurred in the absence of detergent. The results suggest a biochemical role for vitamin A in B. pahangi, possibly in filarial glycoprotein synthesis.

Topics: Animals; beta Carotene; Brugia; Carotenoids; Chromatography, Thin Layer; Diterpenes; Filarioidea; Guanosine Diphosphate Mannose; Male; Microsomes; Microsomes, Liver; Polyisoprenyl Phosphate Monosaccharides; Polyisoprenyl Phosphate Sugars; Rats; Rats, Inbred Strains; Vitamin A

In the presence of Mn(II) ions, the u.v. absorption spectrum of retinyl phosphate (Ret-P) solubilized in Triton X-100 micelles, phosphatidylcholine liposomes or rat liver microsomes exhibited a shift from the maximum of 330 nm to 287 nm. The effect of Mn(II) was reversed by adding EDTA or phosphate buffer. The same spectral change was found in the presence of poly-L-lysine in place of Mn(II) ions. The e.s.r. spectrum of Mn(II) in the presence or in the absence of Ret-P clearly showed that approx. 75% of the initial concentration of Mn(II) ions is bound to Ret-P when the molar ratio of Ret-P to Mn(II) ions is 4:1; no such binding occurred in the presence of retinol or retinoic acid. The appearance of two isosbestic points at 303 and 368 nm, in the presence of Mn(II) ions, suggests the existence of an equilibrium between an Mn(II)-bound monomer and an Mn(II)-bound dimer of Ret-P in Triton X-100 micelles. The same effect on the u.v.-absorption spectrum of Ret-P was also induced by Co(II), Cr(II), Zn(II) and Fe(II), but not by Mg2+ or Cu(II). The formation of the 'metachromatic complex' between Ret-P and Mn(II) or Co(II) inhibited the synthesis of retinyl phosphate mannose (Ret-P-Man) from exogenous and endogenous Ret-P and guanosine diphosphate [14C]mannose when bovine serum albumin was added after the metal ion. However, the order of addition did not influence Ret-P-Man synthesis in incubations containing MgCl2, which does not form the metachromatic complex with Ret-P. These results suggest that the bioavailability of proteins, polyamines and metal ions may control the extent to which Ret-P can be mannosylated in the intact membrane.

Topics: Animals; Cations, Divalent; Diterpenes; In Vitro Techniques; Liposomes; Manganese; Micelles; Microsomes, Liver; Polyisoprenyl Phosphate Monosaccharides; Polylysine; Rats; Spectrophotometry, Ultraviolet; Vitamin A

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Dolichol Monophosphate Mannose; Dolichol Phosphates; Dolichols; Mannose; Mannosephosphates; Polyisoprenyl Phosphate Monosaccharides; Rats; Tretinoin; Vitamin A

Rat liver microsomal fraction synthesized Ret-P-Man (retinyl phosphate mannose) and Dol-P-Man (dolichyl phosphate mannose) from endogenous Ret-P (retinyl phosphate) and Dol-P (dolichyl phosphate). Ret-P-Man synthesis displayed an absolute requirement for a bivalent cation, and also Dol-P-Man synthesis was stimulated by bivalent metal ions. Mn2+ and Co2+ were the most active, with maximum synthesis of Ret-P-Man occurring at 5-10 mM: Mg2+ was also active, but at higher concentrations. At 5mM-Mn2+ the amount of endogenous Ret-P mannosylated in incubation mixtures containing 5 microM-GDP-mannose in 15 min at 37 degrees C was approx. 3 pmol/mg of protein. In the same assays about 7-10 pmol of endogenous Dol-P was mannosylated. Bivalentcation requirement for Ret-P-Man synthesis from exogenous Ret-P showed maximum synthesis at 2.5 mM-Mn2+ or -Co2+. In addition to Ret-P-Man and Dol-P-Man, a mannolipid co-chromatographing with undecaprenyl phosphate mannose was detected. Triton X-100 (0.5%) abolished Ret-P-Man synthesis from endogenous Ret-P and caused a 99% inhibition of Ret-P-Man synthesis from exogenous Ret-P. The presence of detergent (0.5%) also inhibited Dol-P-Man synthesis from endogenous Dol-P and altered the requirement for Mn2+. Microsomal fraction from Syrian golden hamsters was also active in Ret-P-Man and Dol-P-Man synthesis from endogenous Ret-P and Dol-P. At 5 mM-Mn2+ about 2.5 pmol of endogenous Ret-P and 3.7 pmol of endogenous Dol-P were mannosylated from GDP-mannose per mg of protein in 15 min at 37 degrees C. On the other hand, microsomal fraction from vitamin A-deficient hamsters contained 1.2 pmol of Ret-P and 14.1 pmol of Dol-P available for mannosylation. Since GDP-mannose: Ret-P and GDP-mannose: Dol-P mannosyltransferase activities were not affected, depletion of vitamin A must affect Ret-P and Dol-P pools in opposite ways.

Topics: Animals; Cations, Divalent; Chromatography, Thin Layer; Cricetinae; Detergents; Diterpenes; Dolichol Monophosphate Mannose; Dolichol Phosphates; In Vitro Techniques; Kinetics; Male; Mesocricetus; Microsomes, Liver; Octoxynol; Polyethylene Glycols; Polyisoprenyl Phosphate Monosaccharides; Polyisoprenyl Phosphate Sugars; Polyisoprenyl Phosphates; Rats; Serum Albumin, Bovine; Vitamin A; Vitamin A Deficiency

Rat liver microsomes synthesized [14C]mannosylretinylphosphate and dolichyl [14C]mannosylphosphate from guanosinedisphosphate [14C]mannose, retinylphosphate and dolichylphosphate. Two distinct enzyme activities were shown to be responsible for the biosynthesis of the two mannolipids. A higher affinity mannosyl transferase (EA I), responsible for dolichylmannosylphosphate synthesis, displayed a Km for GDP-mannose of 1.7 microM; while a lower affinity enzyme (EA II), responsible for mannosylretinylphosphate synthesis, displayed a Km for GDP-mannose of 12.5 microM. These Km values were unaffected by the addition of either dolichylphosphate for EA II, or retinylphosphate for EA I. The same Km values were found before and after solubilization of the enzyme activity with 1% Triton X-100. Differential solubilization of EA I and EA II was demonstrated, utilizing different concentrations of Triton X-100. Triple-labeled mannosylretinylphosphate was prepared from [3H]retinylphosphate, retinyl[32P]phosphate and GDP-[14C]mannose from incubations containing rat liver microsomes. This compound was shown to donate [14C]mannose to endogenous acceptors of rat liver microsomes.

Topics: Animals; Diterpenes; Dolichol Monophosphate Mannose; Guanosine Diphosphate Mannose; Hexosephosphates; Hexosyltransferases; Kinetics; Mannosephosphates; Mannosyltransferases; Membranes; Microsomes, Liver; Polyisoprenyl Phosphate Monosaccharides; Polyisoprenyl Phosphate Sugars; Polyisoprenyl Phosphates; Rats; Vitamin A

In the absence of detergent, the transfer of mannose from GDP-mannose to rat liver microsomal vesicles was highly stimulated by exogenous retinyl phosphate in incubations containing bovine serum albumin, as measured in a filter binding assay. Under these conditions 65% of mannose 6-phosphatase activity was latent. The transfer process was linear with time up to 5min and with protein concentration up to 1.5mg/0.2ml. It was also temperature-dependent. The microsomal uptake of mannose was highly dependent on retinyl phosphate and was saturable against increasing amounts of retinyl phosphate, a concentration of 15mum giving half-maximal transfer. The uptake system was also saturated by increasing concentrations of GDP-mannose, with an apparent K(m) of 18mum. Neither exogenous dolichyl phosphate nor non-phosphorylated retinoids were active in this process in the absence of detergent. Phosphatidylethanolamine and synthetic dipalmitoylglycerophosphocholine were also without activity. Several water-soluble organic phosphates (1.5mm), such as phenyl phosphate, 4-nitrophenyl phosphate, phosphoserine and phosphocholine, did not inhibit the retinyl phosphate-stimulated mannosyl transfer to microsomes. This mannosyl-transfer activity was highest in microsomes and marginal in mitochondria, plasma and nuclear membranes. It was specific for mannose residues from GDP-mannose and did not occur with UDP-[(3)H]galactose, UDP- or GDP-[(14)C]glucose, UDP-N-acetyl[(14)C]-glucosamine and UDP-N-acetyl[(14)C]galactosamine, all at 24mum. The mannosyl transfer was inhibited 85% by 3mm-EDTA and 93% by 0.8mm-amphomycin. At 2min, 90% of the radioactivity retained on the filter could be extracted with chloroform/methanol (2:1, v/v) and mainly co-migrated with retinyl phosphate mannose by t.l.c. This mannolipid was shown to bind to immunoglobulin G fraction of anti-(vitamin A) serum and was displaced by a large excess of retinoic acid, thus confirming the presence of the beta-ionone ring in the mannolipid. The amount of retinyl phosphate mannose formed in the bovine serum albumin/retinyl phosphate incubation is about 100-fold greater than in incubations containing 0.5% Triton X-100. In contrast with the lack of activity as a mannosyl acceptor for exogenous dolichyl phosphate in the present assay system, endogenous dolichyl phosphate clearly functions as an acceptor. Moreover in the same incubations a mannolipid with chromatographic properties of retinyl phosphate mannose was also synthes

Topics: Animals; Detergents; Diterpenes; Dolichol Monophosphate Mannose; Guanosine Diphosphate Mannose; Immune Sera; In Vitro Techniques; Lipid Metabolism; Male; Microsomes, Liver; Nucleoside Diphosphate Sugars; Octoxynol; Polyethylene Glycols; Polyisoprenyl Phosphate Monosaccharides; Proteins; Rats; Rats, Inbred Strains; Vitamin A

Topics: Animals; Chromatography, High Pressure Liquid; Diterpenes; Intestinal Mucosa; Mice; Organophosphorus Compounds; Polyisoprenyl Phosphate Monosaccharides; Polyisoprenyl Phosphates; Vitamin A