Isolation and characterization of a family of alpha-D-galactosyl-containing glycopeptides from Ehrlich ascites tumor cells.
A family of glycopeptides that contain nonreducing terminal alpha-D-galactosyl residues has been isolated from Pronase digests of delipidated Ehrlich ascites tumor cells. The glycopeptides, which comprise 17.2% of the total plasma membrane hexose, have an average molecular weight of 7500 and are precipitated by Griffonia simplicifolia B4 isolectin, wheat germ agglutinin, and Ricinus communis lectin. Exo- and endoglycosidase digestion, periodate oxidation, permethylation analysis, and lectin reactivity provided evidence for a tentative carbohydrate structure for the glycopeptide mixture. The glycopeptides possess tetraantennary branched structures containing a trimannosyl core N-glycosidically linked via an N,N'-diacetylchitobiosyl unit to an asparagine residue. Each branch contained repeating leads to 3)-beta-D-Galp-(1 leads to 4)-beta-D-GlcNAcp-(1 leads to units resulting in a keratan-like structure, terminated with alpha-D-Galp-(1 leads to 3)-[alpha-D-Galp-(1 leads to 6)]-beta-D-Galp-units. The variation in the molecular weight observed for the glycopeptide mixture can be attributed to the variable amounts of leads to 3)-beta-D-Galp-(1 leads to 4)-beta-D-GlcNAcp-(1 leads to units found in the branch chains.
D000818:Animals; D002240:Carbohydrate Sequence; D002286:Carcinoma, Ehrlich Tumor / Q000648:ultrastructure*; D002462:Cell Membrane / Q000032:analysis*; D002850:Chromatography, Gel; D005690:Galactose / Q000032:analysis*; D006023:Glycoproteins / Q000302:isolation & purification*; D008297:Male; D051379:Mice; D008970:Molecular Weight
D006023:Glycoproteins; D005690:Galactose