title: Isolation and characterization of the N-linked oligosaccharides in nacrein from Pinctada fucata.
abstract: We analyzed the structure of the N-linked oligosaccharides enzymatically liberated from the organic matrix (OM) component in the nacreous layer of Japanese pearl oyster: Pinctada fucata. The lectin-blot analysis of the soluble OM after separation by SDS-PAGE, four components, with sizes of approximately 55 kDa, 35 kDa, 25 kDa, and 21 kDa were detected with GNA lectin, which recognized terminal mannose of high mannose and hybrid types of N-glycan. The 55-kDa component of the soluble OM detected by lectin blotting was identified as nacrein by using liquid chromatography/mass spectrometry (LC/MS). LC/MS analysis of the N-glycan liberated from nacrein detected a hybrid-type N-glycan, which contained sulfite and sialic acid at its terminus. The data strongly imply that nacrein, a sulfated OM glycoprotein, participates in molluscan biomineralization by creating a favorable environment for calcium ion uptake through sulfonic acid and sialic acid.
authors.affiliation: Laboratory for Cell Biology, Department of Environmental Health, Azabu University, Sagamihara-shi, Kanagawa, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Takakura
authors.forename: Michiko
authors.initials: M
authors.lastname: Norizuki
authors.forename: Fumio
authors.initials: F
authors.lastname: Ishikawa
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Samata
mesh_terms: D000818:Animals; D002256:Carbonic Anhydrases / Q000737:chemistry*; D007526:Isoelectric Point; D008358:Mannose / Q000378:metabolism; D009844:Oligosaccharides / Q000737:chemistry* / Q000302:isolation & purification*; D049911:Pinctada / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry; D053719:Tandem Mass Spectrometry
chemical_list: D009844:Oligosaccharides; D011134:Polysaccharides; C101387:nacrein; D002256:Carbonic Anhydrases; D008358:Mannose