Abstract
Recent findings (Ishii, K., Iwasaki, M., Inoue, S., Kenny, P. T. M., Komura, H., and Inoue, Y. (1989) J. Biol. Chem. 264, 1623-1630; Inoue, S., Iwasaki, M., Ishii, K., Kitajima, K., and Inoue, Y. (1989) J. Biol. Chem. 264, 18520-18526) of a relatively large quantity of complex-type free sialo-oligosaccharides in the unfertilized eggs of freshwater fish, Plecoglossus altivelis and Tribolodon hakonensis, prompted us to search for their progenitor glycoproteins. First we demonstrated a third occurrence of free sialoglycans in the unfertilized eggs of Medaka fish (Oryzias latipes). Next, in all three species studied, a uniformly high level of glycophosphoproteins (GPP) was identified and found to possess N-linked glycan units. The carbohydrate structures of the GPP were determined to be identical with those of the free glycans isolated from the unfertilized eggs of the respective fish species. Thus, the most likely candidate for the progenitor of free sialoglycans appeared to be the oocyte GPPs. This implies that the liberation of the free glycans by a putative peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase may represent a necessary biochemical event during vitellogenesis or oogenesis. The present results may provide insight into a new concept of a "protein N-glycosylation/de-N-glycosylation system" recently proposed by us (Seko, A., Kitajima, K., Inoue, Y., and Inoue, S. (1991) J. Biol. Chem. 266, 22110-22114).
Highlights
Fish Egg Glycophosphoproteins HaveSpecies-specific N-Linked Glycan Units Previously Found in a Storage Pool of Free Glycan
First we demonstrated a third occurrence of free sialoglycans in the unfertilized eggs of Medaka fish (Oryzias latipes)
We isolated glycophosphoproteins (GPPs)’ from the unfertilized eggs of Plecoglossus and Tribolodon, determined the structuresof their carbohydrate units, andshowed that they are identical to thoosfefree glycans accumulated in the respective fish eggs
Summary
The aqueous phoafstehe phenol-treated extract solution was evaporatedunder an N, stream.Toluene (1 ml) was obtained from 100 g of fertilized eggs collected within 10h after added to the residue, and the solution was evaporated under an N2 ovulation was dialyzed and applied to a DEAE-Sephadex A-25 column stream. This procedure was repeated four times, and the residue was (1.8 X 79 cm), equilibrated with0.01 M Tris-HC1, pH 8.0, and eluted dried overnight inuacuo over concentrated H,S04.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
