ABSTRACT
This chapter shows that a jelly coat glycoprotein of an extremely large molecular size is the acrosome reaction-inducing substance (ARIS) of the starfish, Asterias amurensis. Fertilizing spermatozoa undergo exocytosis, namely the acrosome reaction, when they reach the extracellular egg-coat. Morphological and physiological changes during the acrosome reaction are well documented in several animals such as sea urchin and starfish. The sugar moiety of ARIS was partially hydrolyzed with mild acid. The mixture of oligosaccharides liberated by mild acid hydrolysis from ARIS retained some activity of ARIS, suggesting that spermatozoa recognize the sugar moiety of ARIS. Main oligosaccharides were purified by gel-filtration and anion-exchange HPLC and analyzed for their structures. All of the oligosaccharides so far analyzed were sulfated and had fucose at the reducing terminus. These results together with published data collectively suggest that the ARIS has fucoidan-like main chains with branches of xylosylgalactose or galactose.
