Changes in protein glycosylation during chick embryo development.
To investigate the molecular changes in cell-surface glycoproteins during chick embryo development, fibroblasts from 8- and 16-day embryos were extensively digested by pronase after (i) metabolic labeling with radioactive precursors and (ii) external labeling. Two main classes of glycopeptide pronase digestion product were distinguished by Sephadex G-50 column chromatography. The large material excluded was mostly composed of glycosaminoglycans. The small retarded glycopeptides underwent age-related modifications. Those in the 8-day cells were mainly N-linked, whereas 16-day cells contained both O- and N-linked glycopeptides. The evolution of high-mannose chains in younger cells to complex-type chains in the older cells is suggested by (i) the decrease in the mannose-to-galactose and mannose-to-N-acetylglucosamine ratio with embryo development, and (ii) the fact that endo-beta-N-acetylglucosaminidase H treatment released more oligomannosyls from younger than from older embryo cell glycopeptides. Small glycopeptides were also more highly sialylated in 16-day cells than in 8-day cells. The present results provide the first biochemical evidence that both quantitative and qualitative modifications occur in cell-surface glycoconjugates during the late stages of chick embryo development.
D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo / Q000502:physiology*; D005347:Fibroblasts / Q000378:metabolism; D006020:Glycopeptides / Q000302:isolation & purification; D006023:Glycoproteins / Q000235:genetics* / Q000302:isolation & purification; D006595:Hexosamines / Q000032:analysis; D008565:Membrane Proteins / Q000235:genetics* / Q000302:isolation & purification; D011499:Protein Processing, Post-Translational
D002241:Carbohydrates; D006020:Glycopeptides; D006023:Glycoproteins; D006595:Hexosamines; D008565:Membrane Proteins