Age-dependent changes in the oligosaccharide structure of the major myelin glycoprotein, P0.
The single oligosaccharide moiety of the major myelin glycoprotein, P0, resides in an immunoglobulin-like domain that appears to participate in homophilic binding. The studies presented here indicate that the structure of the P0 oligosaccharide from rat nerve changes as a function of Schwann cell age. Examination of 5-day-old nerve revealed that P0 contained predominantly endo-beta-N-acetylglucosaminidase H (endo H)-resistant, complex-type oligosaccharide. In contrast, P0 from adult rats had mostly endo H-sensitive carbohydrate, indicating the presence of appreciable high-mannose and/or hybrid-type oligosaccharide on the glycoprotein. The endo H-sensitive and -resistant P0 of adult nerve could be readily phosphorylated by protein kinase C, as could the complex-type P0 from 5-day-old nerve. This suggests that the glycoprotein progresses to the plasma membrane and myelin regardless of the type of oligosaccharide chain. Analysis of 35SO4(2-)-labeled P0 showed that the sulfate group was found on both endo H-sensitive and -resistant oligosaccharide. The endo H-sensitive P0 carbohydrate from adult nerve appears to be primarily of the hybrid type, as evidenced by (a) the elution profile of [3H]mannose-labeled P0 glycopeptides from adult nerve during concanavalin A chromatography and (b) the inability of P0 from adult nerve to interact with Galanthus nivalis agglutinin. The observed age-dependent changes of P0 oligosaccharide may modify the binding properties of this myelin glycoprotein.
Department of Biochemistry, University of Mississippi Medical Center, Jackson.
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Brunden
D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D027801:Galanthus; D006596:Hexosaminidases / Q000494:pharmacology; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D018993:Myelin P0 Protein; D009185:Myelin Proteins / Q000737:chemistry* / Q000378:metabolism; D009844:Oligosaccharides / Q000737:chemistry*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051381:Rats; D011919:Rats, Inbred Strains; D012584:Sciatic Nerve / Q000378:metabolism
D018993:Myelin P0 Protein; D009185:Myelin Proteins; D009844:Oligosaccharides; D006596:Hexosaminidases; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase