title: Sugar-binding sites with specificity to N-acetyl-D-glucosaminides in middle ear mucosa of the guinea pig.
abstract: The distribution of sugar-binding sites was analyzed in Lowicryl K4M-embedded guinea pig middle ear mucosa. Four neoglycoproteins and a glycoprotein were used as probes: N-acetyl-D-glucosamine (GlcNAc), D-mannose, N-acetyl-D-galactosamine, or L-fucose carrying bovine serum albumin (BSA) and asialofetuin with terminal D-galactosyl sugar residues. Each probe was then labelled with 15 nm colloidal gold. Incubation of ultrathin sections with gold-labelled p-aminophenyl N-acetyl-beta-D-glucosaminide-BSA (GlcNAc/BSA/gold) led to binding on mucosal cilial, microvilli, rough endoplasmic reticulum, mitochondria, and nuclei. No binding occurred with asialofetuin or neoglycoproteins containing mannose, N-acetylgalactosamine or fucose. Various control experiments showed that specificity of GlcNAc/BSA/gold binding was directed towards N-acetylglucosaminyl residues expressed on the neoglycoprotein. Competitive sugar inhibition with GlcNAc and its derivatives suggested that the strong affinity for GlcNAc-binding sites took place in a complex formation with sugar residues bound to a carrier protein. The existence of a hydrophobic region close to the sugar-binding site was also suggested.
authors.affiliation: Department of Otolaryngology, Municipal Yamashiro Hospital, Kyoto, Japan.
authors.forename: F
authors.initials: F
authors.lastname: Tanimura
authors.forename: H
authors.initials: H
authors.lastname: Morioka
mesh_terms: D000116:Acetylgalactosamine / Q000378:metabolism; D000117:Acetylglucosamine / Q000378:metabolism; D000818:Animals; D001212:Asialoglycoproteins / Q000378:metabolism; D001665:Binding Sites; D002236:Carbohydrate Conformation; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002923:Cilia / Q000000981:diagnostic imaging; D004432:Ear, Middle / Q000378:metabolism* / Q000648:ultrastructure; D004721:Endoplasmic Reticulum / Q000378:metabolism; D060748:Fetuins; D005643:Fucose / Q000378:metabolism; D017979:Gold Colloid; D006168:Guinea Pigs; D008358:Mannose / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D009092:Mucous Membrane / Q000378:metabolism / Q000648:ultrastructure; D011971:Receptors, Immunologic / Q000378:metabolism*; D034781:Receptors, N-Acetylglucosamine; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013194:Staining and Labeling; D014463:Ultrasonography; D000509:alpha-Fetoproteins / Q000378:metabolism
chemical_list: D001212:Asialoglycoproteins; D060748:Fetuins; D017979:Gold Colloid; D011971:Receptors, Immunologic; D034781:Receptors, N-Acetylglucosamine; D000509:alpha-Fetoproteins; C017029:asialofetuin; C053610:fucose-bovine serum albumin conjugate; D012710:Serum Albumin, Bovine; D005643:Fucose; D000116:Acetylgalactosamine; D008358:Mannose; D000117:Acetylglucosamine