A. Brandelli et al., PARTICIPATION OF GLYCOSYLATED RESIDUES IN THE HUMAN SPERM ACROSOME REACTION - POSSIBLE ROLE OF N-ACETYLGLUCOSAMINIDASE, Biochimica et biophysica acta. Molecular cell research, 1220(3), 1994, pp. 299-304
Sperm binding to the egg zona pellucida is mediated by complementary p
rotein-carbohydrate interaction. This binding results in the exocytosi
s of the sperm acrosome, or acrosome reaction (AR). We report the effe
ct of different neoglycoproteins (sugar residues covalently bound to b
ovine serum albumin) on the human sperm AR. p-Aminophenyl-N-acetyl-bet
a-D-glucosaminide-BSA (BSA-GlcNAc) and p-aminophenyl-alpha-D-mannopyra
noside-BSA (BSA-Man) at 1 mu g/ml were capable of inducing the greates
t percentages of AR (3-fold stimulation with respect to controls), whi
le other NeoGPs had only a weak effect on this process. The BSA-GlcNAc
-induced acrosome reaction was inhibited by N-acetylglucosamine (GlcNA
c), p-nitrophenyl-GlcNAc, and purified soluble beta-N-acetylglucosamin
idase (beta NAG). The induction of the AR with BSA-Man could be inhibi
ted by mannose, while soluble alpha-mannosidase was only partially eff
ective. These data suggest that binding sites for GlcNAc and mannose m
ay be involved in the induction of the AR in human sperm. The characte
ristics of the BSA-GlcNAc induction suggest that the beta NAG molecule
may be the mediator of this effect.