Relationship between cell surface asparagine-linked glycoproteins and myoblast differentiation. Analysis of wheat germ agglutinin-resistant mutants

Abstract

Alterations in the oligosaccharides of complex surface glycoproteins have been studied in wild-type rat skeletal myoblasts (L6-9/1) and two wheat germ agglutinin resistant mutants, selected for either high level of resistance (WGARI) or low level of resistance (WGARII). All three lines possessed high mannose oligosaccharides of the structure Mann GlcNAc, where n = 6, 7, or 8. L6-9/1 had complex oligosaccharides of the type (±NeuNAcα2-3GalβGlcNAcβ)nMan3GlcNAc(±Fuc)GlcNAc where n = 3 or 4, in addition to small amounts of biantennary and higher order structures. WGARII, the mutant with low resistance to wheat germ agglutinin, possessed similar complex oligosaccharides except that they had undergone some base-sensitive modification which rendered them resistant to Clostridium perfringens sialidase. WGARI, mutant of high resistance to wheat germ agglutinin, possessed complex oligosaccharides of the type (GlcNAcβ)nMan3GlcNAc(±Fuc)GlcNAc, with n = 2,3, or 4. Since the WGARI mutants were unaltered in differentiation, it is concluded that the terminal sialic acid and galactose residues on the protein-bound oligosaccharides are not required for differentiation.