Inhibition of sea urchin sperm acrosome reaction by antibodies directed against two sperm membrane proteins. Characterization and mechanism of action.
The egg jelly-induced acrosome reaction is inhibited by polyclonal antibodies raised against either of two S. purpuratus sperm-membrane proteins, of Mr 80 and 210 kD. Although the two antigens used have dissimilar CNBr peptide maps, antisera produced against each of them cross-react with both proteins. Inhibition of the egg jelly-induced acrosome reaction by the antisera is bypassed by a combination of the ionophores monensin and A23187. This result, along with data showing that the antisera inhibit egg jelly-induced uptake of 45Ca2+, suggests that the antisera may block both Ca2+ uptake and Na+/H+ exchange in the sperm. The acrosome reaction blockage appears to be caused by the same component of the polyclonal sera responsible for cross-reaction; consequently, these antisera cannot be used to determine whether one or both of the cross-reacting proteins modulate a critical step in the acrosome reaction.
D000177:Acrosome / Q000502:physiology*; D000818:Animals; D000906:Antibodies; D000936:Antigen-Antibody Complex; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology; D005455:Fluorescent Antibody Technique; D005779:Immunodiffusion; D007700:Kinetics; D008297:Male; D008565:Membrane Proteins / Q000302:isolation & purification / Q000502:physiology*; D008970:Molecular Weight; D012617:Sea Urchins; D013094:Spermatozoa / Q000502:physiology*
D000906:Antibodies; D000936:Antigen-Antibody Complex; D008565:Membrane Proteins; D002118:Calcium