Differential expression of MAG isoforms during development

J Neurosci Res. 1991 Jun;29(2):141-8. doi: 10.1002/jnr.490290202.


The myelin-associated glycoproteins (MAG) mediate the cell interactions of oligodendrocytes and Schwann cells with axons that are myelinated. MAG exists in two developmentally regulated isoforms: large MAG (L-MAG) and small MAG (S-MAG). In this paper, we have studied the tissue-specific and developmentally regulated alternative splicing of these isoforms using monospecific antibodies that recognize epitopes common to both isoforms or that are present only on L-MAG. In the central nervous system (CNS), L-MAG is the major form synthesized early in development, and it persists as a significant proportion of the MAG present in the adult. In the peripheral nervous system (PNS), L-MAG is expressed at modest levels during development; it is virtually absent in the adult. Thus, the expression of L-MAG is not limited to the CNS, as was formerly believed, suggesting that it plays a common role during the early stages of myelin formation by both oligodendrocytes and Schwann cells. In both the CNS and PNS, S-MAG is the predominant isoform in the adult. A higher-molecular-weight form of MAG is present in the PNS at low abundance, that is developmentally regulated, and appears to be a glycosylation variant. An analysis of the carbohydrate residues on MAG demonstrates that it contains both N-linked and O-linked sugars that could be modulated during development. These results suggest a possible mechanism for the regulation of MAG function during myelinogenesis via the expression of alternative isoforms and carbohydrate modifications.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Antibodies / immunology
  • Antibody Specificity
  • Brain Stem / growth & development
  • Brain Stem / metabolism
  • Immunoblotting
  • Isomerism
  • Myelin Proteins / immunology
  • Myelin Proteins / metabolism*
  • Myelin-Associated Glycoprotein
  • Oligosaccharides / chemistry
  • Oligosaccharides / metabolism
  • Rats
  • Sciatic Nerve / growth & development
  • Sciatic Nerve / metabolism


  • Antibodies
  • Myelin Proteins
  • Myelin-Associated Glycoprotein
  • Oligosaccharides