Estimation by radiation inactivation of the minimum functional size of acrosome-reaction-including substance (ARIS) in the starfish,Asterias amurensis

Abstract

SummaryIn the starfishAsterias amurensis, the jelly coat of the eggs contains a glycoprotein essential for the induction of the acrosome reaction in homologous spermatozoa that is termed the acrosome-reaction-inducing substance (ARIS).ARIS is a highly sulphated and fucose-rich glycoprotein of extremely high molecular mass(>104kDa). ARIS was irradiated with high-energy eletrons in order to estimate the minimum size required for its biological activity. The minimum functional unit or target size of ARIS was estimated to bec. 14 kDa by target size analysis. ARIS was significantly disintegrated by the irradiation, yet the total sugar content was not apparently reduced. The binding of125I-labelled ARIS to spermatozoa competed with that of irradiated ARIS, although the affinity of ARIS was much reduced after irradiation.