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Test

VIth ICA - Symposium - Molecular Mechanisms of sperm egg interaction (1996)

Dr. J. M. White (USA) reviewed molecules which mediate sperm-egg binding and fusion. Her group and others have identified two sets of cell surface proteins-sperm ADAMs and egg integrins that are involved. Sperm ADAMs, a heterodimeric complex (fertilin a/b), are made on early spermatogenic cells as ~100Kd precursor proteins that are proteolytically processed during spermatogenesis to mature forms which lack the pro and metalloprotease domains. From experiments on the binding of fertilin conjugated beads to egg and some other lines of evidence she suggested the disintegrin domain of fertilin b would play an important role in sperm-egg binding.

Since ion channels play key role in the mammalian acrosome reaction, A. Darszon (Mexico) studied the expression of the alpha1 genes which code for the channel subunit of the various types of voltage-activated Ca channels in spermatogenic cells. His laboratory also developed an assay system of ion channels in a single sperm. T-type Ca currents were detected in pachytene spermatocytes and Dr. Darszon indicated that T-type Ca channels play a key role in the Ca uptake required for the acrosomal reaction of mammalian sperm.

Dr. J. M. White (USA) reviewed molecules which mediate sperm-egg binding and fusion. Her group and others have identified two sets of cell surface proteins-sperm ADAMs and egg integrins that are involved. Sperm ADAMs, a heterodimeric complex (fertilin a/b), are made on early spermatogenic cells as ~100Kd precursor proteins that are proteolytically processed during spermatogenesis to mature forms which lack the pro and metalloprotease domains. From experiments on the binding of fertilin conjugated beads to egg and some other lines of evidence she suggested the disintegrin domain of fertilin b would play an important role in sperm-egg binding. Since ion channels play key role in the mammalian acrosome reaction, A. Darszon (Mexico) studied the expression of the alpha1 genes which code for the channel subunit of the various types of voltage-activated Ca channels in spermatogenic cells. His laboratory also developed an assay system of ion channels in a single sperm. T-type Ca currents were detected in pachytene spermatocytes and Dr. Darszon indicated that T-type Ca channels play a key role in the Ca uptake required for the acrosomal reaction of mammalian sperm.

Yoshitake Nishimune, Japan