Wheat germ agglutinin blocks the acrosome reaction in Strongylocentrotus purpuratus sperm by binding a 210,000-mol-wt membrane protein.
Wheat germ agglutinin (WGA) binds to the entire surface of Strongylocentrotus purpuratus sperm, and inhibits the egg jelly-induced acrosome reaction. The binding was found to be species dependent and was completely inhibited by 5 mM N-acetyl-D-glucosamine. Blockage of the acrosome reaction by WGA was bypassed by a combination of the ionophores A23187 and monensin, although neither ionophore was effective individually. These experiments suggest that WGA blocks both Ca2+ uptake and Na+/H+ exchange in these sperm, which was confirmed by direct measurements of 45Ca2+ uptake and H+ efflux. The target of WGA in S. purpuratus sperm appears to be a membrane glycoprotein of Mr = 210,000. Treatment of this protein with neuraminidase or endo-beta-N-acetylglucosaminidase F abolished WGA binding.
D000117:Acetylglucosamine / Q000494:pharmacology; D000177:Acrosome / Q000502:physiology*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D037102:Lectins / Q000494:pharmacology*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008970:Molecular Weight; D008985:Monensin / Q000494:pharmacology; D009439:Neuraminidase / Q000494:pharmacology; D011522:Protons; D011975:Receptors, Mitogen / Q000187:drug effects / Q000378:metabolism*; D012617:Sea Urchins / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D013045:Species Specificity; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*; D014909:Wheat Germ Agglutinins
D037102:Lectins; D008565:Membrane Proteins; D011522:Protons; D011975:Receptors, Mitogen; D014909:Wheat Germ Agglutinins; C027503:wheat germ agglutinin receptor; D000001:Calcimycin; D008985:Monensin; D012964:Sodium; D009439:Neuraminidase; D002118:Calcium; D000117:Acetylglucosamine