Zona pellucida-mediated signal transduction in mammalian spermatozoa
Kopf, G.S.
Journal of Reproduction and Fertility. Supplement 42: 33-49
1990
ISSN/ISBN: 0449-3087 PMID: 2127605 Document Number: 358630
A review of work in laboratory mammals. Spermatozoa for all species studied contain G proteins. The presence of such signal-transducing proteins suggests that the regulation of sperm function involves control elements which are similar to ligand:receptor:G protein:2nd messenger systems in many somatic cells. This hypothesis is supported by experiments which demonstrate an intermediary role for the mouse sperm Gi-like protein in ZP3-induced acrosomal exocytosis. The specific function of the Gi-like protein is not known, although possible roles in regulating ionic movements, cyclic nucleotide metabolism and polyphosphoinositide turnover should be considered. Studies directed at the location and biochemical identity of the mouse sperm Gi-like protein, as well as the nature of the 2nd messenger system(s)/ionic events modulated by this protein, are in progress. From studies of the egg-induced polyspermy block, it appears that the induction of the acrosome reaction may involve multiple interactions between ZP3 moieties and complementary binding sites (receptors) on the sperm surface. This is consistent with other studies, suggesting that aggregation of sperm-associated ZP3 receptors may be responsible for the induction of the complete acrosome reaction.