Structural studies of a novel type of pentaantennary large glycan unit in the fertilization-associated carbohydrate-rich glycopeptide isolated from the fertilized eggs of Oryzias latipes.
In a previous report (Kitajima, K., Inoue, S., and Inoue, Y. (1989) Dev. Biol. 132, 544-553), we found the presence of a heavily glycosylated polyprotein, "H-hyosophorin," isolated from the unfertilized eggs of Oryzias latipes. We now report our detailed analysis of the structure of the N-glycan chain in L-hyosophorin, the smallest repeating unit of H-hyosophorin, which was isolated from the fertilized eggs of O. latipes and formed from H-hyosophorin upon fertilization. The N-glycan structures were defined by a combination of compositional analysis, methylation analysis, selective chemical degradation (i.e. mild methanolysis, periodate-Smith degradation, and hydrazinolysis-nitrous acid deamination), enzymatic (endo-beta-galactosidase, peptide:N-glycanase, and Newcastle disease virus sialidase) digestion, and instrumental analyses (one- and two-dimensional proton nuclear magnetic resonance spectroscopy and fast atom bombardment mass spectrometry) which revealed novel and unique features: (a) the presence of highly branched poly-N-acetylactosamino pentaantennary structures; (b) the presence of a beta-galactosylated Lewis X antigenic epitope, Gal beta 1-->4 Gal beta 1-->4 (Fuc alpha 1-->3) GlcNAc beta 1-->; (c) the presence of a beta-galactosylated sialyl Lewis X structure, Gal beta 1-->4 (Neu5Ac alpha 2-->3) Gal beta 1-->4(Fuc alpha 1-->3) GlcNAc beta 1-->; (d) the presence of Gal beta 1-->4 Gal beta 1--> and Gal beta 1--> 4Gal beta 1-->4Gal beta 1--> as the major and minor groupings, respectively; and (e) the presence of the branched Gal residues, -->4GlcNAc beta 1-->3(Gal beta 1-->4) Gal beta 1-->. This study represents the first detailed investigation regarding the nature of highly branched complex asparagine-linked pentaantennary glycans in glycoproteins. The unique expression of such bulky multiantennary glycan units on proteins could be essential during early embryogenesis.
Taguchi
T
T
Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
Seko
A
A
Kitajima
K
K
Muto
Y
Y
Inoue
S
S
Khoo
K H
KH
Morris
H R
HR
Dell
A
A
Inoue
Y
Y
D000818:Animals; D002240:Carbohydrate Sequence; D002849:Chromatography, Gas; D005306:Fertilization; D029941:Fish Proteins; D005399:Fishes / Q000502:physiology*; D008401:Gas Chromatography-Mass Spectrometry; D006023:Glycoproteins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011134:Polysaccharides / Q000737:chemistry*; D013045:Species Specificity; D015053:Zygote / Q000737:chemistry*
D029941:Fish Proteins; D006023:Glycoproteins; D011134:Polysaccharides; C061150:hyosophorin protein, Fish