Fertilization: a step closer to understanding the mechanism

Photo Credit: PhotoResearchers

"Researchers at Karolinska Institutet in Sweden have taken a step closer to understanding the mechanism that leads to the fusion of egg and sperm at fertilisation. Using the technique X-ray crystallography, they have determined the 3D structure of Juno, a mammalian egg protein essential for triggering gamete fusion. Their findings are not only interesting from an evolutionary perspective, but also reveal the shape of a possible target for future non-hormonal contraceptives.

The fusion of egg and sperm is an essential step of fertilisation in sexually reproducing organisms and the molecular mechanism behind this event has long been the object of intense research. A breakthrough came in 2014 with the discovery of Juno, a protein receptor found on the egg. Juno, which is tethered to the cell membrane of the egg, binds to sperm surface protein Izumo1 when egg and sperm meet.

The discovery of Juno and Izumo1 opened up new possibilities to study the process of fertilisation at the molecular level. The importance of both molecules was demonstrated when experiments showed that mice lacking either of them are infertile. However, how Juno interacts with Izumo1 was unclear, something that Luca Jovine, Professor of Structural Biology at the Department of Biosciences and Nutrition and the Center for Innovative Medicine, has worked hard to understand..."

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