N-Linked Oligosaccharides of Sea Urchin Egg Jelly Induce the Sperm Acrosome Reaction: (fertilization/acrosome reaction/sea urchin/sperm/N-linked oligosaccharides).

ABSTRACT

The sea urchin egg jelly coat (EJ) induces the acrosome reaction (AR) of sperm. We previously demonstrated that a fraction of EJ containing two glycoproteins of 82- and 138-kDa possess the AR inducing activity (8). Here we show that Peptide-N-Glycosidase-F treatment of EJ followed by precipitation and washing in 70% ethanol results in a substantial loss of AR inducing activity in the ethanol insoluble material. When a PNGase-F digest of EJ is chromatographed on a Sepacryl-200 gel filtration column, an AR inducing fraction elutes within the partitioning volume. Acrosome reaction inducing activity of undigested EJ does not elute within the partitioning volume. The chromatographed AR inducing fraction of the PNGase-F digest reacts strongly in the phenol-sulfuric assay demonstrating carbohydrate is present; silver stained gels do not detect the presence of protein. Harsh alkaline hydrolysis of EJ in an excess of NaBH4 , preserves a substantial amount of AR inducing activity. These data show that N-linked oligosaccharides released from EJ by PNGase-F digestion are capable of inducing the sperm acrosome reaction.