title: Specific strychnine binding sites on acrosome-associated membranes of golden hamster spermatozoa.
abstract: This study demonstrates for the first time, that membrane vesicles originated from the hamster sperm head after the occurrence of the acrosome reaction, possess specific strychnine binding sites. [3H]Strychnine binding was saturable and reversible, being displaced by unlabeled strychnine (IC(50)=26.7+/-2.3 microM). Kinetic analysis revealed one binding site with K(d)=120nM and B(max)=142fmol/10(6) spermatozoa. Glycine receptor agonists beta-alanine and taurine inhibited strychnine binding by 20-30%. Surprisingly, glycine stimulated binding by about 40-50%. Results obtained in this study strongly suggest the presence of glycine receptors-with distinctive kinetic properties on the periacrosomal plasma membrane of hamster spermatozoa. Localization of this receptor fits well with its previously proposed role in acrosomal exocytosis during mammalian fertilization.
authors.affiliation: Unidad de Hormonas y Receptores, INTA, Universidad de Chile, Casilla # 138-11, Santiago, Chile. mllanos@uec.inta.uchile.cl
authors.forename: Miguel N
authors.initials: MN
authors.lastname: Llanos
authors.forename: Ana M
authors.initials: AM
authors.lastname: Ronco
authors.forename: María C
authors.initials: MC
authors.lastname: Aguirre
mesh_terms: D020101:Acrosome Reaction; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D003292:Convulsants / Q000494:pharmacology; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D005306:Fertilization; D005998:Glycine / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008297:Male; D008647:Mesocricetus; D011485:Protein Binding; D013081:Sperm Motility; D013094:Spermatozoa / Q000378:metabolism*; D013331:Strychnine / Q000737:chemistry*; D013654:Taurine / Q000494:pharmacology; D015091:beta-Alanine / Q000494:pharmacology
chemical_list: D003292:Convulsants; D015091:beta-Alanine; D013654:Taurine; D013331:Strychnine; D005998:Glycine