Protein-bound glycogen is linked to tyrosine residues.
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.
Aon
M A
MA
Curtino
J A
JA
D000681:Amylases / Q000378:metabolism; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D006003:Glycogen / Q000378:metabolism*; D007457:Iodine Radioisotopes; D046911:Macromolecular Substances; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
D007457:Iodine Radioisotopes; D046911:Macromolecular Substances; D011506:Proteins; D014443:Tyrosine; D006003:Glycogen; D000681:Amylases