ISOLATION AND CHARACTERIZATION OF HIGH-MOLECULAR-WEIGHT GLYCOPROTEINSFROM EMBRYONATED EGGS OF EMERITA-ASIATICA

The main yolk protein of Emerita asiatica is comprised fo glycolipopro tein conjugated to carotenoid pigment. In the present study the embroy nated eggs of the mole crab, Emerita asiatica, were tested for the pre sence of O-linked glycoproteins. The high molecular weight glycoprotei n was extracted in 0.2 M phosphate buffer, pH 6.0 with 8 M urea and fr actionated by size exclusion chromatography on Sephorase CL 4B column using the same buffer system. The high molecular weight glycoprotein w as excluded and the included peak contained low molecular weight glyco proteins. The rechromatographed void fraction from the delipidated egg homogenate was free of low molecular weight components as confirmed b y SDS-PAGE. I-125 wheat germ agglutinin and peanut agglutinin overlay and the recently developed modified Morgan-Elson assay confirm that th e egg contains mucin-type glycoproteins. Monosaccharide analysis of th e void fraction was performed. High performance anionic exchange chrom atography (HPAEC) shows the presence of GaINAc, GlcNAc, galactose, fuc ose, mannose and glucose. The identified and characterized high molecu lar weight glycoprotein is a new class which may play a role in the re ceptor mediated uptake of vitellogenin, a yolk precursor protein synth esized elsewhere.