title: The myelin-associated glycoprotein of the peripheral nervous system in trembler mutants contains increased alpha 2-3 sialic acid and galactose.
abstract: The myelin-associated glycoprotein (MAG) exhibits an abnormally high apparent molecular weight in sciatic nerve, but not in brain, of dysmyelinating trembler mutants (Inuzuka et al.: J Neurochem 44:793-797, 1985). Antibodies to the large and small isoforms of MAG (L- and S-MAG) and probes for oligosaccharide structure were used to determine if this was due to overexpression of L-MAG or increased glycosylation. Nerves from both control and trembler 36-day-old mice contained primarily S-MAG with only traces of L-MAG. The distribution of the two isoforms appeared normal in trembler mice, and both isoforms exhibited the higher apparent molecular weight. Lectin binding showed that, in contrast to brain in which most glycoproteins contain primarily alpha 2-3 linked sialic acid, most glycoproteins of both control and trembler nerve contained primarily alpha 2-6 linked sialic acid. Lectin binding and glycosidase treatments demonstrated that the higher molecular weight of MAG in trembler nerves was due to an increased content of alpha 2-3 linked sialic acid and galactose. The abnormal glycosylation of MAG in trembler mutants may contribute to the myelin pathology.
authors.affiliation: Myelin and Brain Development Section, Laboratory of Molecular and Cellular Neurobiology, NINDS, NIH, Bethesda, Maryland, USA.
authors.forename: Z P
authors.initials: ZP
authors.lastname: Bartoszewicz
authors.forename: C J
authors.initials: CJ
authors.lastname: Lauter
authors.forename: R H
authors.initials: RH
authors.lastname: Quarles
mesh_terms: D000818:Animals; D005690:Galactose / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000494:pharmacology; D006031:Glycosylation; D007536:Isomerism; D037102:Lectins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008818:Mice, Neurologic Mutants; D008970:Molecular Weight; D018992:Myelin-Associated Glycoprotein / Q000737:chemistry / Q000378:metabolism*; D010525:Peripheral Nerves / Q000378:metabolism*; D012016:Reference Values; D012794:Sialic Acids / Q000378:metabolism*
chemical_list: D006023:Glycoproteins; D037102:Lectins; D018992:Myelin-Associated Glycoprotein; D012794:Sialic Acids; D006026:Glycoside Hydrolases; D005690:Galactose