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Zonadhesin: characterization, localization, and zona pellucida binding
I A Lea1, P Sivashanmugam, M G O'Rand
1Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, 27599, USA. ialea@email.unc.edu
Biology of Reproduction
|November 22, 2001
Summary
Zonadhesin, a sperm protein, is processed into fragments that bind the zona pellucida after the acrosome reaction. This binding is crucial for sperm-egg interaction during fertilization.
Area of Science:
- Reproductive Biology
- Molecular Endocrinology
- Cell Biology
Background:
- Zonadhesin is a transmembrane protein implicated in sperm-zona pellucida binding.
- Understanding zonadhesin's role is key to deciphering fertilization mechanisms.
Purpose of the Study:
- To investigate zonadhesin's processing, expression, localization, and zona pellucida binding in rabbits.
- To elucidate the functional significance of zonadhesin during fertilization.
Main Methods:
- Sequencing of rabbit zonadhesin.
- Analysis of protein processing, mRNA expression, and cellular localization.
- In vitro binding assays using recombinant zonadhesin domains.
Main Results:
- Zonadhesin precursor is testis-specific; processed into p43, p97, and p58 fragments.
- Fragments form disulfide-bonded dimers in mature spermatozoa.
- Zonadhesin mRNA is synthesized in primary spermatocytes; protein abundant in Sertoli cells and spermatids.
- In spermatozoa, zonadhesin localizes to the anterior acrosome and is released with the acrosomal shroud post-acrosome reaction.
- Recombinant D4 domain binds the zona pellucida.
Conclusions:
- Zonadhesin functions post-acrosome reaction, mediating binding via the acrosomal shroud.
- The D4 domain is critical for zona pellucida interaction.