Tissue specific O-linked glycosylation of the neural cell adhesion molecule (N-CAM).
We have shown previously that the predominant N-CAM isoform in skeletal muscle myotubes contains as a result of alternative splicing a novel domain (MSD1) in its extracellular region. Here we show that this region represents a site for O-linked carbohydrate attachment. The lipid tailed N-CAM in myotubes was found to bind peanut lectin while the transmembrane isoform from myoblasts lacking MSD1 did not. In addition, N-CAM from a variety of neural sources failed to bind the lectin. Analysis of 3T3 fibroblasts transfected with various N-CAM cDNAs, showed that peanut lectin binding was correlated specifically with the expression of the MSD1 region. The oligosaccharides isolated from a purified preparation of myotube N-CAM were shown to contain an O-linked oligosaccharide whose core structure was a sialylated version of Gal beta 1----3GalNac which is the structure recognized specifically by peanut lectin. These data provide the first evidence for the expression of O-linked carbohydrate on any N-CAM isoform and more specifically target this oligosaccharide to the MSD1 region of myotube N-CAM.
Walsh
F S
FS
Department of Neurochemistry, Institute of Neurology, Queen Square, London, UK.
Parekh
R B
RB
Moore
S E
SE
Dickson
G
G
Barton
C H
CH
Gower
H J
HJ
Dwek
R A
RA
Rademacher
T W
TW
D001345:Autoradiography; D015153:Blotting, Western; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism*; D004586:Electrophoresis; D006031:Glycosylation; D006801:Humans; D037102:Lectins / Q000378:metabolism; D009132:Muscles / Q000166:cytology / Q000196:embryology*; D019887:Peanut Agglutinin
D015816:Cell Adhesion Molecules, Neuronal; D037102:Lectins; D019887:Peanut Agglutinin