Scientists found protein that joins egg with sperm

Fertilization takes place when an egg cell and a sperm cell recognize one another and fuse to form an embryo. But how they recognize each other in order to hook up had remained a mystery.

Researchers said they have identified a protein on the egg cell's surface that interacts with another protein on the surface of a sperm cell, allowing the two cells to join, the Fox News reported.

This protein, dubbed Juno in honor of the ancient Roman goddess of fertility and marriage, and its counterpart in sperm, named Izumo after a Japanese marriage shrine, are essential for reproduction in mammals including people, they said.

This new understanding of the role of these two proteins could help improve the treatment of infertility and guide the development of new contraceptives, the researchers said.

The researchers are now screening infertile women to try to determine whether problems with the Juno receptor are to blame.

Gavin Wright of the Welcome Trust Sanger Institute in Britain said that if defects in the Juno receptor are in fact implicated in human infertility, a simple, non-invasive genetic screening test could be developed to identify affected women.

"This then would allow us to guide the fertility treatment," Wright said, letting affected women proceed directly to a procedure called intracytoplasmic sperm injection involving direct injection of sperm into an egg obtained from in vitro fertilization.

The Sanger Institute researchers made an artificial version of Izumo to try to find an answer, and found that it interacted with Juno to initiate fertilization. They then developed mice that lacked Juno. The females of these mice were infertile because their egg cells did not fuse with sperm.

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