A PROTEIN that plays a crucial role in conception could be the key to creating a contraceptive that doesn’t tinker with a woman’s hormones.
The coating of mammalian eggs contains a protein called ZP3, which sperm must bind to if they are to burrow through the coating and fertilise the egg. Female mice engineered to lack ZP3 do not have this coating, making them infertile, while women with abnormal ZP3 may also suffer fertility problems.
Luca Jovine at the Karolinska Institute in Huddinge, Sweden, and his colleagues have used X-ray crystallography to work out the chemical structure of a stretch of mouse ZP3 that gives the protein its structural properties (Nature, ). As the equivalent stretch of human ZP3 is likely to be similar in structure, Jovine says it may be possible to design drugs that bind to ZP3, thereby preventing the coating from forming and rendering women temporarily infertile.
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Such a drug might avoid some of the side effects of today’s oral contraceptives, which disrupt hormone production throughout the body.
