Evidence for the existence of O-linked sugar chains consisting of glucose and xylose in bovine thrombospondin.
We have recently discovered unusual sugar chains [xylose-glucose and (xylose)2-glucose] linked to a serine residue in the first epidermal growth factor (EGF)-like domains of human and bovine coagulation factors VII, IX, and protein Z. The sequence surrounding this serine residue has a common -Cys-X-Ser-X-Pro-Cys- structure. Since one (residues 533-538) of the three EGF-like domains found in human thrombospondin contains the conserved sequence, we examined the presence of such O-linked sugar chains in bovine thrombospondin (bTSP) and its 210-kDa fragment. Component sugar analysis after pyridylamination (PA) of the acid hydrolysates of the S-aminoethylated proteins revealed that the proteins contain glucose (Glc) and xylose (Xyl). The oligosaccharide moieties released from intact bTSP by hydrazinolysis followed by pyridylamination were separated into two PA-oligosaccharides by high performance liquid chromatography (HPLC). Component sugar analysis of these PA-oligosaccharides indicated that they consist of Glc and Xyl in molar ratios of 1:1 and 1:2 (or 1:3). The reducing ends of both PA-sugar chains were found to be PA-Glc, as judged from the retention time of the HPLC peak of their hydrolysates. The presence of these PA-sugar chains in bTSP was confirmed by HPLC mapping with two different columns, using standard PA-di- or PA-trisaccharide derived from coagulation factors. From these results, we concluded that bTSP contains O-linked sugar chains consisting of Glc and Xyl in one of its three EGF-like domains.
Nishimura
H
H
Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka.
Yamashita
S
S
Zeng
Z
Z
Walz
D A
DA
Iwanaga
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D050260:Carbohydrate Metabolism; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000737:chemistry*; D002417:Cattle; D002645:Chickens; D004815:Epidermal Growth Factor / Q000737:chemistry; D005947:Glucose / Q000737:chemistry*; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism; D019699:Thrombospondins; D014994:Xylose / Q000737:chemistry*
D002241:Carbohydrates; D009844:Oligosaccharides; D010446:Peptide Fragments; D010980:Platelet Membrane Glycoproteins; D019699:Thrombospondins; C011274:3-hydroxyaspartic acid; D001224:Aspartic Acid; D004815:Epidermal Growth Factor; D014994:Xylose; D005947:Glucose