Structures of the asparagine-linked sugar chains of laminin.
This investigation describes the isolation and characterization of oligosaccharides of the basement membrane glycoprotein, laminin. Pronase-released glycopeptides of isolated laminin, from a mouse Engelbreth-Holm-Swarm tumor, were fractionated using a combination of gel permeation chromatography and Con A-Sepharose affinity chromatography. The glycopeptides were analyzed for sugar linkage patterns by methylation analysis. Glycopeptides and hydrazine-released oligosaccharides were further analyzed using endo-beta-galactosidase, endo-beta-N-acetylglucosaminidase H and specific exoglycosidases in conjunction with calibrated gel permeation chromatography. Based on these experiments, murine tumor laminin was shown to contain asparagine-linked oligosaccharides with the following structures: bi-, tri- and tetraantennary complex-type oligosaccharides; polylactosaminyl side chains containing Gal(beta 1----4)GlcNAc(beta 1----3) repeating units attached to the trimannose core portion of the bi-, tri- and tetraantennary complex-type oligosaccharides; unusual complex-type oligosaccharides terminated at the nonreducing end with sialic acid, alpha-galactose, beta-galactose and beta-N-acetylglucosamine; alpha-galactosyl residues linked to N-acetyllactosamine sequences; high-mannose-type oligosaccharides. These results, in conjunction with analytical data, indicate that most of the carbohydrate of this laminin is N-linked to asparagine and that there are about 43 such N-linked oligosaccharides per laminin molecule.
D000818:Animals; D001216:Asparagine; D001485:Basement Membrane / Q000032:analysis; D002236:Carbohydrate Conformation; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D005690:Galactose / Q000032:analysis; D005944:Glucosamine / Q000032:analysis; D006020:Glycopeptides / Q000032:analysis; D007797:Laminin / Q000032:analysis*; D051379:Mice; D008970:Molecular Weight; D009374:Neoplasms, Experimental / Q000032:analysis; D009844:Oligosaccharides / Q000032:analysis*
D006020:Glycopeptides; D007797:Laminin; D009844:Oligosaccharides; D001216:Asparagine; D005944:Glucosamine; D005690:Galactose