title: New tandem-repeating peptide structures in polysialoglycoproteins from the unfertilized eggs of kokanee salmon.
abstract: New polysialoglycoproteins, designated PSGP(On), were isolated from the fertilized and unfertilized eggs of the kokanee salmon, Oncorhynchus nerka adonis. The polysialylglycan chains consisting of alpha-2,8-linked O-acetylated poly(N-glycolylneuraminyl) chains have recently been characterized. We have now determined the complete amino acid sequence of the tandem-repeating units of PSGP(On) from the unfertilized eggs of kokanee salmon and found that the following two distinct forms are present in PSGP(On) in almost identical amounts: [formula: see text] and [formula: see text] where * denotes the O-glycosylation site and mean value of m, n = about 20. Upon fertilization these high-molecular-weight forms of PSGP(On) were proteolytically cleaved to the corresponding repeating units, low-molecular-weight PSGP(On), by the action of a specific protease (PSGPase) at the position two residues set C-terminally to the Pro residue and N-terminally to the Asp residue, i.e. -Pro-Ser-Xaa-Asp-: [formula: see text] and [formula: see text].
authors.affiliation: Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Song
authors.forename: K
authors.initials: K
authors.lastname: Kitajima
authors.forename: Y
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001483:Base Sequence; D002241:Carbohydrates / Q000032:analysis; D005260:Female; D005306:Fertilization; D008969:Molecular Sequence Data; D009439:Neuraminidase; D010063:Ovum / Q000737:chemistry*; D012474:Salmon; D012689:Sequence Homology, Nucleic Acid; D012795:Sialoglycoproteins / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D012795:Sialoglycoproteins; D009439:Neuraminidase