Occurrence of terminal alpha 2-->8-linked disialylated poly-N-acetyllactosamine chains with Le(X) and I antigenic glycotopes in tetraantennary arms of an N-linked glycoprotein isolated from rainbow trout ovarian fluid.
The Pronase digestion of a 54K glycoprotein present in ovarian fluid of rainbow trout yielded a major glycopeptide. Carbohydrate compositional analysis revealed that this glycopeptide was likely to possess a single large N-glycan chain having low molecular weight oligomers of N-acetylneuraminic acid (oligoNeu5Ac). Structural studies of this glycopeptide revealed novel alpha 2-->8-linked disialylated poly-N-acetyllactosamine chains with Le(X) and I antigenic determinants on the N-linked tetraantennary core glycan. In our recent studies (Kitazume,S., Kitajima,K., Inoue,S., Inoue,Y. and Troy,F.A. (1994) J. Biol. Chem. 269, 10330-10340) we presented evidence that synthesis of alpha 2-->8-linked polysialic acid (polySia) chains is a two-step process in which chain initiation is catalyzed by an alpha 2-->8-sialyltransferase (alpha 2-->8-ST; initiase) that catalyzes synthesis of the first Sia alpha 2-->8-linkage, forming the disialic acid (diSia) unit, Sia alpha 2-->8-Sia alpha 2-->6-Gal-. Chain polymerization is then postulated to be catalyzed by a second enzyme, an alpha 2-->8-polyST ("polymerase") that converts the diSia units to polySia chains. The present structural studies leading to the discovery of alpha 2-->8-linked disialylated units that terminate poly-N-acetyllactosamine chains in an N-linked glycoprotein is further evidence in support of our hypothesis that more than one sialyltransferase activity is required for polySia chain synthesis and polymerization.
Funakoshi
Y
Y
Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Japan.
Taguchi
T
T
Sato
C
C
Kitajima
K
K
Inoue
S
S
Morris
H R
HR
Dell
A
A
Inoue
Y
Y
D000818:Animals; D002240:Carbohydrate Sequence; D002845:Chromatography; D000939:Epitopes; D005260:Female; D006868:Hydrolysis; D016256:Lewis X Antigen; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss; D010053:Ovary / Q000737:chemistry* / Q000276:immunology; D011134:Polysaccharides / Q000737:chemistry* / Q000276:immunology; D017421:Sequence Analysis; D012795:Sialoglycoproteins / Q000737:chemistry* / Q000276:immunology; D016339:Spectrometry, Mass, Fast Atom Bombardment
D000939:Epitopes; D016256:Lewis X Antigen; D011134:Polysaccharides; D012795:Sialoglycoproteins; C037199:poly-N-acetyllactosamine