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Gene Review

Mag  -  myelin-associated glycoprotein

Mus musculus

Synonyms: Gma, Myelin-associated glycoprotein, Siglec-4a, siglec-4a
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Disease relevance of Mag


Psychiatry related information on Mag

  • Despite their motor deficits, Mag- and Galgt1-null mice demonstrated hyperactivity, with spontaneous locomotor activity significantly above that of wild type mice [6].

High impact information on Mag

  • Crosslinking of large MAG with antibody induces a rapid increase in the specific activity of Fyn kinase [7].
  • In Krox-20-/- mice, Schwann cells wrap their cytoplasmic processes only one and a half turns around the axon, and although they express the early myelin marker, myelin-associated glycoprotein, late myelin gene products are absent, including those for protein zero and myelin basic protein [8].
  • 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 [9].
  • 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 [9].
  • Furthermore, the over- or underexpression of MAG in transfected Schwann cells in vitro leads to accelerated myelination or hypomyelination, respectively [9].

Chemical compound and disease context of Mag

  • Expression of the two forms of MAG mRNA was studied here in experimentally introduced demyelination and remyelination by Cuprizone intoxication [10].

Biological context of Mag


Anatomical context of Mag


Associations of Mag with chemical compounds


Enzymatic interactions of Mag


Regulatory relationships of Mag


Other interactions of Mag

  • Furthermore, the developmental change between the two molecular forms of MAG (p72MAG/p67MAG) was delayed in mld mice [15].
  • Myelin-associated glycoprotein and other proteins in Trembler mice [24].
  • Immunoblotting analysis did not reveal an increased apparent Mr for MAG in the Jimpy mouse, as has been observed in some other hypomyelinating murine mutants [25].
  • No abnormal accumulation of MAG, MBP, or CNP in the cell body was found [26].
  • In the current studies, CNS and PNS histopathology and behavior of Mag-null, Galgt1-null, and double-null mice were compared on the same mouse strain background [6].

Analytical, diagnostic and therapeutic context of Mag

  • Immunoblotting analysis did not reveal an increased apparent Mr for MAG, as has been observed in quaking and trembler mice [27].
  • Furthermore, at 8 weeks of age, single fiber preparation and electron microscopy revealed that the number of profiles indicative of degeneration was substantially increased in MAG-/N-CAM- mutants when compared to MAG- mice [28].
  • We have adapted the gene-targeting approach in embryonic stem cells to generate mutant mice that express a truncated form of the L-MAG isoform, eliminating the unique portion of its cytoplasmic domain, but that continue to express S-MAG [29].
  • These results demonstrate that MAG expression is regulated in response to cortical axotomy, and indicate that it may limit axonal regeneration after CNS injury [30].
  • Using antisera specific for L- and S-MAG, respectively, it was shown that S-MAG is the principal isoform in quaking mice at all ages between 13 and 72 days, although L-MAG was just detectable by western blotting at the early ages [31].


  1. Immunocytochemical localization of MAG, MBP and P0 protein in acute and relapsing demyelinating lesions of Theiler's virus infection. Dal Canto, M.C., Barbano, R.L. J. Neuroimmunol. (1985) [Pubmed]
  2. Schwann cells infected with a recombinant retrovirus expressing myelin-associated glycoprotein antisense RNA do not form myelin. Owens, G.C., Bunge, R.P. Neuron (1991) [Pubmed]
  3. Immunoelectron microscopic localization of neural cell adhesion molecules (L1, N-CAM, and MAG) and their shared carbohydrate epitope and myelin basic protein in developing sciatic nerve. Martini, R., Schachner, M. J. Cell Biol. (1986) [Pubmed]
  4. Soluble myelin-associated glycoprotein released from damaged white matter inhibits axonal regeneration. Tang, S., Qiu, J., Nikulina, E., Filbin, M.T. Mol. Cell. Neurosci. (2001) [Pubmed]
  5. Myelin-associated glycoprotein shares an antigenic determinant with a glycoprotein of human melanoma cells. Noronha, A.B., Harper, J.R., Ilyas, A.A., Reisfeld, R.A., Quarles, R.H. J. Neurochem. (1986) [Pubmed]
  6. Myelin-associated glycoprotein and complementary axonal ligands, gangliosides, mediate axon stability in the CNS and PNS: neuropathology and behavioral deficits in single- and double-null mice. Pan, B., Fromholt, S.E., Hess, E.J., Crawford, T.O., Griffin, J.W., Sheikh, K.A., Schnaar, R.L. Exp. Neurol. (2005) [Pubmed]
  7. Initial events of myelination involve Fyn tyrosine kinase signalling. Umemori, H., Sato, S., Yagi, T., Aizawa, S., Yamamoto, T. Nature (1994) [Pubmed]
  8. Krox-20 controls myelination in the peripheral nervous system. Topilko, P., Schneider-Maunoury, S., Levi, G., Baron-Van Evercooren, A., Chennoufi, A.B., Seitanidou, T., Babinet, C., Charnay, P. Nature (1994) [Pubmed]
  9. Myelination in the absence of myelin-associated glycoprotein. Li, C., Tropak, M.B., Gerlai, R., Clapoff, S., Abramow-Newerly, W., Trapp, B., Peterson, A., Roder, J. Nature (1994) [Pubmed]
  10. Induction of myelin-associated glycoprotein mRNA in experimental remyelination. Fujita, N., Ishiguro, H., Sato, S., Kurihara, T., Kuwano, R., Sakimura, K., Takahashi, Y., Miyatake, T. Brain Res. (1990) [Pubmed]
  11. Myelin-associated glycoprotein is a myelin signal that modulates the caliber of myelinated axons. Yin, X., Crawford, T.O., Griffin, J.W., Tu, P., Lee, V.M., Li, C., Roder, J., Trapp, B.D. J. Neurosci. (1998) [Pubmed]
  12. Binding of soluble myelin-associated glycoprotein to specific gangliosides induces the association of p75NTR to lipid rafts and signal transduction. Fujitani, M., Kawai, H., Proia, R.L., Kashiwagi, A., Yasuda, H., Yamashita, T. J. Neurochem. (2005) [Pubmed]
  13. Chromosomal location of the mouse gene that encodes the myelin-associated glycoproteins. D'Eustachio, P., Colman, D.R., Salzer, J.L. J. Neurochem. (1988) [Pubmed]
  14. Phase separation of myelin proteins in triton X-114: differential behavior of myelin basic protein in purified myelin and in cultured oligodendrocytes. Bürgisser, P., Matthieu, J.M. Dev. Neurosci. (1989) [Pubmed]
  15. Myelin instability and oligodendrocyte metabolism in myelin-deficient mutant mice. Matthieu, J.M., Roch, J.M., Omlin, F.X., Rambaldi, I., Almazan, G., Braun, P.E. J. Cell Biol. (1986) [Pubmed]
  16. The effect of the mouse mutation claw paw on myelination and nodal frequency in sciatic nerves. Koszowski, A.G., Owens, G.C., Levinson, S.R. J. Neurosci. (1998) [Pubmed]
  17. Myelin-associated glycoprotein in the central and peripheral nervous system of quaking mice. Inuzuka, T., Johnson, D., Quarles, R.H. J. Neurochem. (1987) [Pubmed]
  18. Gene expression in brain during cuprizone-induced demyelination and remyelination. Morell, P., Barrett, C.V., Mason, J.L., Toews, A.D., Hostettler, J.D., Knapp, G.W., Matsushima, G.K. Mol. Cell. Neurosci. (1998) [Pubmed]
  19. The endogenous lectin cerebellar soluble lectin and its ligands in central nervous system myelin of myelin-deficient (mld) mutant mice. Kuchler, S., Zanetta, J.P., Zaepfel, M., Badache, A., Sarliève, L.L., Vincendon, G., Matthieu, J.M. J. Neurochem. (1991) [Pubmed]
  20. The immunoglobulin-superfamily molecule basigin is a binding protein for oligomannosidic carbohydrates: an anti-idiotypic approach. Heller, M., von der Ohe, M., Kleene, R., Mohajeri, M.H., Schachner, M. J. Neurochem. (2003) [Pubmed]
  21. Myelin basic protein and myelin-associated glycoprotein in chronic, relapsing experimental allergic encephalomyelitis. Sternberger, N.H., McFarlin, D.E., Traugott, U., Raine, C.S. J. Neuroimmunol. (1984) [Pubmed]
  22. MAG-deficient Schwann cells myelinate dorsal root ganglion neurons in culture. Carenini, S., Montag, D., Schachner, M., Martini, R. Glia (1998) [Pubmed]
  23. Cells positive for the O4 surface antigen isolated by cell sorting are able to differentiate into astrocytes or oligodendrocytes. Trotter, J., Schachner, M. Brain Res. Dev. Brain Res. (1989) [Pubmed]
  24. Myelin-associated glycoprotein and other proteins in Trembler mice. Inuzuka, T., Quarles, R.H., Heath, J., Trapp, B.D. J. Neurochem. (1985) [Pubmed]
  25. Jimpy mice: quantitation of myelin-associated glycoprotein and other proteins. Yanagisawa, K., Quarles, R.H. J. Neurochem. (1986) [Pubmed]
  26. His36Pro point-mutated proteolipid protein retained in the endoplasmic reticulum of oligodendrocytes in the shaking pup. Song, J., Goetz, B.D., Duncan, I.D. Glia (2006) [Pubmed]
  27. Myelin-deficient rat: analysis of myelin proteins. Yanagisawa, K., Duncan, I.D., Hammang, J.P., Quarles, R.H. J. Neurochem. (1986) [Pubmed]
  28. Absence of the myelin-associated glycoprotein (MAG) and the neural cell adhesion molecule (N-CAM) interferes with the maintenance, but not with the formation of peripheral myelin. Carenini, S., Montag, D., Cremer, H., Schachner, M., Martini, R. Cell Tissue Res. (1997) [Pubmed]
  29. The cytoplasmic domain of the large myelin-associated glycoprotein isoform is needed for proper CNS but not peripheral nervous system myelination. Fujita, N., Kemper, A., Dupree, J., Nakayasu, H., Bartsch, U., Schachner, M., Maeda, N., Suzuki, K., Popko, B. J. Neurosci. (1998) [Pubmed]
  30. Overexpression of myelin-associated glycoprotein after axotomy of the perforant pathway. Mingorance, A., Fontana, X., Soriano, E., Del Río, J.A. Mol. Cell. Neurosci. (2005) [Pubmed]
  31. Abnormal expression and glycosylation of the large and small isoforms of myelin-associated glycoprotein in dysmyelinating quaking mutants. Bartoszewicz, Z.P., Noronha, A.B., Fujita, N., Sato, S., Bö, L., Trapp, B.D., Quarles, R.H. J. Neurosci. Res. (1995) [Pubmed]
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