A monoclonal antibody to human SP-10 inhibits in vitro the binding of human sperm to hamster oolemma but not to human zona pellucida

Toshio Hamatani, Kiyoo Tanabe, Kiyoshi Kamei, Nozomi Sakai, Yurie Yamamoto, Yasunori Yoshimura

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

SP-10 is a sperm intra-acrosomal protein, specific to the testis, that is believed to play an important role in egg-sperm binding. While the molecular characterization of the SP-10 protein has been clarified, little is yet known of its functional role in fertilization. We therefore established a monoclonal antibody (mAb pep-SP10) against a peptide (pep-SP10) that included the most hydrophilic portion of human SP-10 between the 135th and 149th amino acids. Human SP-10 was found to be localized in the equatorial region of acrosome-reacted sperm by immunofluorescent staining using our mab pep-SP10. Monoclonal Ab pep-SP10 inhibited sperm-oolemma binding in the zona-free hamster egg penetration test, but it did not inhibit sperm-zona binding in the hemizona assay. Furthermore, we demonstrated that the oolemmal ligands of human SP-10 did not include β1 integrins, the most promising candidates for oocyte ligands involved in sperm-oolemma binding, based on the findings of a human sperm-cultured cell binding assay using F9 mouse embryonal carcinoma cells and F9-transformed cells lacking β1 integrins. In conclusion, our present data suggest that human SP10, expressed on the equatorial region of acrosome-reacted sperm, indeed mediates sperm-oolemma binding in a β1 integrin-independent manner, but not sperm-zona binding.

Original languageEnglish
Pages (from-to)1201-1208
Number of pages8
JournalBiology of reproduction
Volume62
Issue number5
DOIs
Publication statusPublished - 2000 Jan 1

ASJC Scopus subject areas

  • Reproductive Medicine
  • Cell Biology

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