In order to design a male contraceptive, scientists must understand the molecules involved with sperm fertilization of the egg and each step of the fertilization process. Photo by videodoctor/Shutterstock

CHARLOTTESVILLE, Va., June 24 (UPI) -- Researchers have discovered a protein that stabilizes the site where a sperm transforms to fuse with the egg before fertilization, which may help eventually lead to a male contraceptive.

Understanding the molecular processes that occur when sperm fuse with eggs in the reproductive process should reveal molecules that can block or disrupt fertilization, researchers said. The protein discovery is a very early part of that process.


When a sperm binds to an egg, enzymes transform the head of the sperm, which results in a loss of proteins, except for one called ESP1 that appears to initiate the fusion and stabilize the site where it is happening.

"We don't know enough yet about the protein-protein interactions here to be able to come up with a defined male contraceptive strategy so it's pretty early in the process of seeing where a small molecule drug might interdict these interactions," Dr. John Herr, of the Center for Research in Contraceptive and Reproductive Health at the University of Virginia, said in a press release. "We need to figure out the other partner proteins with which ESP1 is interacting."

In order to design a male contraceptive, scientists first need to define the molecules involved with fertilization, understand their locations throughout the fertilization process and then can begin looking for ways to block it, Herr said.

The study is published in Biology of Reproduction.