The results of the research conducted by scientists at the Karolinska Institute will lead to a better understanding of infertility and may enable entirely new types of contraceptives.
“The results give a remarkable picture of the female side of fertilisation. But this is, of course, only half of the story. The next step will be to tackle the corresponding molecules on sperm that allow it to bind to the egg,” Karolinska’s Luca Jovine, who led the study, said in a statement.
The results were published online in the journal Cell on Thursday.
At conception, sperm binds to proteins in the extracellular coat of the egg, called zona pellucida. However, prior to the discovery, the molecular details of the event had remained obscure.
Jovine’s research team at Karolinska has now managed to determine the three-dimensional structure of the receptor molecule that binds sperm, called ZP3.
The detailed structural information was based on data collected at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The findings makes it possible to begin exploring how the egg interacts with sperm at fertilisation at the molecular level.
The study suggests which parts of the receptor are likely to be directly contacted by sperm, and provides new insights into how the sperm receptor is assembled and secreted from the egg.
The findings have important implications for human reproductive medicine and can possibly explain how mutations in the sperm receptor gene can result in infertility. The research could also potentially lead to the design of non-hormonal contraceptives specifically targeting egg-sperm interaction.