Myelination in the absence of myelin-associated glycoprotein

Nature. 1994 Jun 30;369(6483):747-50. doi: 10.1038/369747a0.


The hypothesis that myelin-associated glycoprotein (MAG) initiates myelin formation is based in part on observations that MAG has an adhesive role in interactions between oligodendrocytes and neurons. Furthermore, the over- or underexpression of MAG in transfected Schwann cells in vitro leads to accelerated myelination or hypomyelination, respectively. Here we test this idea by creating a null mutation in the mag locus and deriving mice that are totally deficient in MAG expression at the RNA and protein level. In adult mutant animals the degree of myelination and its compaction are normal, whereas the organization of the periaxonal region is partially impaired. Mutant animals show a subtle intention tremor. Our findings do not support the widely held view that MAG is critical for myelin formation but rather indicate that MAG is necessary for maintenance of the cytoplasmic collar and periaxonal space of myelinated fibres.

Publication types

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

MeSH terms

  • Animals
  • Cell Line
  • Female
  • Male
  • Mice
  • Motor Activity
  • Mutagenesis
  • Myelin Proteins / genetics
  • Myelin Proteins / physiology*
  • Myelin Sheath / chemistry
  • Myelin Sheath / physiology*
  • Myelin Sheath / ultrastructure
  • Myelin-Associated Glycoprotein
  • Nerve Fibers, Myelinated
  • Optic Nerve / cytology
  • Posture
  • RNA, Messenger / metabolism
  • Schwann Cells / physiology
  • Schwann Cells / ultrastructure
  • Sciatic Nerve / cytology
  • X-Ray Diffraction


  • Myelin Proteins
  • Myelin-Associated Glycoprotein
  • RNA, Messenger