ANALYSIS FOR THE ROLE OF HUMAN SPERM ACROSOMAL MOLECULEH-SP-1 IN SIGNAL TRANSDUCTION VIA CALCIUM CHANNEL

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Several surface molecules of both gametes are involved in gametes recognition during fertilization (Saling, 1989). These molecules are responsible for each process of fertilizationand species-specific interaction between the gametes. Studies of these molecules may be essential for understanding the mechanism of sperm-egg interaction and for the development of a contraceptive vaccine.We isolated a human sperm antigen gene (h-Sp-1) by screening from human testis cDNA library with human sperm specific antisera. The sequence analysis of the h-Sp-1 gene indicated that it contained 2170 bp and had 45% homology to human synaptophysin gene, which was considered to play a crucial role in calcium dependent signal transduction in synaptic vesicles in the terminal end of nerves. The analysis of the deduced amino acids from the h-Sp-1 gene showed that it encoded 259 amino acids containing four hydrophilic regions and four hydrophobic regions. This indicated that the molecules encoded by the h-Sp-1 … More gene might be a transmembrane protein with four membrane spanning regions like the synaptophysin. Northern blot analysis indicated that h-Sp-1 gene had 2 kind of transcripts (2.3 kb and 1.1kb). 2.3kb transcript expressed ubiquitously whereas 1.1kb transcript expressed abundantly in human testis. In order to characterizethe molecules encoded by the h-Sp-1 gene, the antisera were generated by immunizing rabbits with synthetic polypeptides (amino acid No 174-198) based on the h-Sp-1 gene. Western blot analysis indicated that the antisera reacted a 40 kDa molecule. The antisera also stained fixed human sperm head by indirect immunofluorescence staining. The purified antisera showed the inhibitory effect on human sperm penetration assay into zona-free hamster eggs. We also analyzed the localization of h-Sp-1 molecule by electoromicroscpy. The result indicated the molecule exist on surface of whole sperm head. This h-Sp-1 seemed to be associaed with calmodulin, syntax in according to western blot analysis. activities. Less