A study recently published in the journal Molecular & Cellular Proteomics has identified on the surface of the bovine sperm 58 proteins able to recognize sugar molecules present on the surface of ova involved in the fertilization process.

The formation of the egg cells that eventually give rise to a new living being depends on the union between the male (sperm) and female (egg) gametes.  This union is preceded by a series of cell interactions that will first lead the sperm towards the fallopian tubes then to allow their fusion with the nucleus of the egg. Like many other living processes, the interactions described are based on the specific recognition between sugar and protein molecules, an essential but not always sufficiently recognized dialogue in biology.

Using technology developed in their own laboratory, scientists of the Proteomics and Protein Chemistry group at Pompeu Fabra University led by David Andreu and Ricardo Gutiérrez-Gallego, with the collaboration of Manuel Avilés of the University of Murcia, have been able to detect for the first time 58 sperm proteins capable of binding to sugars and are responsible for cell interactions mentioned above. These proteins, called lectins, are seen to be involved in two crucial stages of fertilization: sperm reservoir formation in the oviduct epithelium and sperm-egg interaction.

The proteins identified in this study are in many cases identical to those of human semen and, as the authors say, “they contain structural information that could be used, among other purposes, to facilitate infertility diagnosis and treatment or for developing future vaccines to control fertility”.

Reference work: Sira Defaus, Manuel Avilés, David Andreu, Ricardo Gutiérrez-Gallego. Identification of bovine sperm surface proteins involved in carbohydrate-mediated fertilization interactions. Molecular & Cellular Proteomics, April 2016.  doi:10.1074/mcp.M115.057703