Protein-bound glycogen is linked to tyrosine residues

Biochemical Journal (Impact Factor: 4.4). 08/1985; 229(1):269-72. DOI: 10.1042/bj2290269
Source: PubMed


Tyrosine-glycogen obtained from retina proteoglycogen by exhaustive proteolytic digestion was radiolabelled with 125I. The 125I-labelled tyrosine-glycogen was degraded by amylolytic digestion to a very small radioactive product, which was identified as iodotyrosine by h.p.l.c. The amylolytic mixture used released glucose and maltose that were alpha-linked to the phenolic hydroxy group of p-nitrophenol. No free iodotyrosine was found before or after the intact [125I]iodotyrosine-glycogen was subjected to two cycles of the Edman degradation procedure. The linkage between protein and glycogen was alkali-stable. Therefore it is concluded that the protein-bound glycogen was O-glycosidically linked to the phenolic hydroxy group of tyrosine. The amino acid has not been heretofore found to be involved in the linkage of carbohydrates to proteins.

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Available from: Miguel A Aon
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    • "catalyzing two autoglucosylation reactions using UDP-glucose as donor substrate (Fig. 1A). First, a glucose-O-tyrosine linkage is formed with the hydroxyl group of tyrosine 195 [10] [11] [12] [13] [14] and second, several α1,4 glucosidic linkages are formed to produce an oligosaccharide containing approximately 8–13 glucose residues [13] [15] [16]. The priming oligosaccharide chain is required for elongation by glycogen synthase (EC "
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    ABSTRACT: Glycogenin-1 initiates the glycogen synthesis in skeletal muscle by the autocatalytic formation of a short oligosaccharide at tyrosine 195. Glycogenin-1 catalyzes both the glucose-O-tyrosine linkage and the α1,4 glucosidic bonds linking the glucose molecules in the oligosaccharide. We recently described a patient with glycogen depletion in skeletal muscle as a result of a non-functional glycogenin-1. The patient carried a Thr83Met substitution in glycogenin-1. In this study we have investigated the importance of threonine 83 for the catalytic activity of glycogenin-1. Non-glucosylated glycogenin-1 constructs, with various amino acid substitutions in position 83 and 195, were expressed in a cell-free expression system and autoglucosylated in vitro. The autoglucosylation was analyzed by gel-shift on western blot, incorporation of radiolabeled UDP-(14)C-glucose and nano-liquid chromatography with tandem mass spectrometry (LC/MS/MS). We demonstrate that glycogenin-1 with the Thr83Met substitution is unable to form the glucose-O-tyrosine linkage at tyrosine 195 unless co-expressed with the catalytically active Tyr195Phe glycogenin-1. Our results explain the glycogen depletion in the patient expressing only Thr83Met glycogenin-1 and why heterozygous carriers without clinical symptoms show a small proportion of unglucosylated glycogenin-1.
    Full-text · Article · Dec 2011 · Biochimica et Biophysica Acta
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    • "Covalent attachment of glycans to the protein backbone via the amide nitrogen of an asparagine residue (N-glycosylation) or via the hydroxyl group of serine, threonine or hydroxyproline (O-glycosylation) has been reported for many natural glycoproteins (Varki et al. 1999). In contrast, as a rare event, in insect larvae (Chen et al. 1978; Kramer et al. 1980) as well as in glycogenin of glycogen-containing eukaryotic cells (Aon and Curtino 1985; Rodriguez and Whelan 1985), an Oglycosidic linkage between a tyrosine residue and α-D-glucose has been observed. In prokaryotes, O-glycosidic linkages of glycans via β-D-galactose or β-D-glucose residues to tyrosine βwere discovered as completely new types of linkage in the Slayer glycoproteins of Paenibacillus alvei, Thermoanaerobacter thermohydrosulfuricus and Thermoanaerobacterium thermosaccharolyticum strains, respectively (Christian et al. 1988; Altman et al. 1991, 1995; Messner et al. 1992, 1995; Bock et al. 1994; Schäffer et al. 2000). "
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    ABSTRACT: Glycosylation is a frequent and heterogeneous posttranslational protein modification occurring in all domains of life. While protein N-glycosylation at asparagine and Oglycosylation at serine, threonine or hydroxyproline residues have been studied in great detail, only few data are available on O-glycosidic attachment of glycans to the amino acid tyrosine. In this study, we describe the identification and characterization of a bacterial protein tyrosine O-glycosylation system. In the Gram-positive, mesophilic bacterium Paenibacillus alvei CCM 2051T, a polysaccharide consisting of [→3)-β-D-Galp-(1[α-DGlcp-(1→6)] →4)-β-D-ManpNAc-(1→] repeating units is O-glycosidically linked via an adaptor with the structure -[GroA-2→OPO2→4-β-D-ManpNAc-(1→4)] →3)-α-LRhap-(1→3)-α-L-Rhap-(1→3)-α-L-Rhap-(1→3)-β-DGalp-(1→ to specific tyrosine residues of the S-layer protein SpaA. A ~24.3-kb S-layer glycosylation (slg) gene cluster encodes the information necessary for the biosynthesis of this glycan chain within 18 open reading frames (ORF). The corresponding translation products are involved in the biosynthesis of nucleotide-activated monosaccharides, assembly and export as well as in the transfer of the completed polysaccharide chain to the S-layer target protein. All ORFs of the cluster, except those encoding the nucleotide sugar biosynthesis enzymes and the ATP binding cassette (ABC) transporter integral transmembrane proteins, were disrupted by the insertion of the mobile group II intron Ll. LtrB, and S-layer glycoproteins produced in mutant backgrounds were analyzed by mass spectrometry. There is evidence that the glycan chain is synthesized in a process comparable to the ABC-transporter-dependent pathway of the lipopolysaccharide O-polysaccharide biosynthesis.Furthermore, with the protein WsfB, we have identified an O-oligosaccharyl:protein transferase required for the formation of the covalent β-D-Gal→Tyr linkage between the glycan chain and the S-layer protein. © The Author 2010. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: [email protected] /* */
    Full-text · Article · Mar 2010 · Glycobiology
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