Researchers Isolate Proteins That Allow Sperm To Penetrate Egg.

2001 MAR 22 - (NewsRx.com & NewsRx.net) -- A team of proteins vital to fertility because of their ability to send signals that allow sperm to pass through an egg membrane has been isolated by researchers at two universities in the United States.

The finding, says David J. Miller of the University of Illinois, is a small step in itself but a leap forward in the study of infertility. "We've gotten inside the door and past the first step," he said. "We believe we are looking at a single pathway, but one that may have alternatives along the way."

Miller's group of UI researchers and Barry D. Shur of Emory University in Atlanta, Georgia, reported in the February 2001 issue of the journal Development that once sperm binds to the protein coat of an egg, a group of G proteins activate. Their subsequent signaling activity opens the gate for sperm to enter.

Shur had reported in 1996 that the protein galactosyl transferase (GalTase) on sperm binds to the protein ZP3 on the zona pellucida - a coat around all mammalian eggs. However, his findings were contradictory: when GalTase was absent, fertility did not stop in mice, but during m vitro fertilization experiments, a lack of GalTase severely compromised sperms' ability to penetrate the zona pellucida.

The new research strengthens and advances Shur's earlier discovery, said Miller, a UI professor of animal science who did postdoctoral research under Shur. This time, researchers focused on ZP3 with a series of molecular experiments that combined components of sperm from mice ...