Purification and characterization of two glycoproteins from oligodendroglial plasma membranes

Two major glycoproteins of 99 kDa and 77 kDa have been purified from oligodendroglial plasma membranes. These two glycoproteins exhibit intense binding to the lectin, wheat germ agglutinin. The 99-kDa and 77-kDa glycoproteins were purified by Sephadex LH-60 chromatography, wheat germ agglutinin affinity chromatography and SDS-polyacrylamide pore gradient gel electrophoresis. Re-electrophoresis of excised gel slices containing the two glycoproteins demonstrated their apparent homogeneity. The isoelectric points of the 99-kDa and 77-kDa glycoproteins were 6.15 and 6.00, respectively. Peptide mapping revealed structural differences between the two glycoproteins. Lectin binding studies with radiolabeled succinylated wheat germ agglutinin demonstrated that the binding of the 99-kDa and 77-kDa glycoproteins to wheat germ agglutinin was due to N-acetyl-D-glucosamine residues in the oligosaccharide side-chains.