Characterization of the oligosaccharide units of the bovine erythrocyte membrane glycoprotein.
The major glycoprotein of the bovine erythrocyte membrane was purified by extraction of the ghosts with lithium 3,5-diiodosalicylate followed by phenol-water extraction and acidification. The glycoprotein contains 20% protein and 80% carbohydrate by weight and gives a single band on sodium dodecyl sulfate-polyacrylamide gels with an estimated molecular weight of 230000 daltons. The carbohydrate composition of the glycoprotein was determined to be (in residues relative to sialic acid): sialic acid, 1.0; fucose, less than 0.01; mannose, 0.1; galactose, 3.3; N-acetylgalactosamine, 0.9; and N-acetylglucosamine, 2.4. Pronase digestion of the isolated glycoprotein followed by Sephadex G-75 gel filtration resulted in the separation of a small pool of glycopeptides (pool III), which included all of the mannose-containing glycopeptides, from the bulk of the glycopeptide material which was in the void fractions of the column (pool I). Alkaline borohydride treatment released over 95% of the oligosaccharide units in pool I and approximately 30% of the oligosaccharide units in pool III. These oligosaccharides were isolated by gel filtration and ion-exchange chromatography. The oligosaccharides released from pool I had molecular weights of 1100-1400 daltons and contained sialic acid, galactose, and N-acetylglucosamine in molar ratios of 0.5-1:3:2 as well as a partial residue of N-acetylgalactosaminitol. The oligosaccharides released from pool III by alkali had molecular weights of 1300-1600 daltons and contained sialic acid, galactose, N-acetylglucosamine, N-acetylgalactosamine and N-ACETYLgalactosaminitol in molar ratios of 1-2:2:1:1:1. These data indicate that the majority of the oligosaccharide units of the bovine erythrocyte glycoprotein are linked O-glycosidically to the peptide backbone of the molecule.
D000116:Acetylgalactosamine / Q000032:analysis; D000117:Acetylglucosamine / Q000032:analysis; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000032:analysis*; D004912:Erythrocytes / Q000032:analysis*; D005643:Fucose / Q000032:analysis; D005690:Galactose / Q000032:analysis; D006023:Glycoproteins / Q000097:blood*; D008358:Mannose / Q000032:analysis; D008970:Molecular Weight; D009844:Oligosaccharides / Q000097:blood*; D012794:Sialic Acids / Q000032:analysis
D006023:Glycoproteins; D009844:Oligosaccharides; D012794:Sialic Acids; D005643:Fucose; D000116:Acetylgalactosamine; D008358:Mannose; D000117:Acetylglucosamine; D005690:Galactose