Apr. 23, 2007 Researchers have discovered a new protein involved in the fertilization of an egg by sperm, providing useful information for scientists developing reproductive technologies and for better understanding reproductive disorders.
When the membranes of the sperm head and egg start fusing and create an opening between them, the sperm cell releases proteins through the opening that activate the egg. This allows the sperm cell to further enter the egg and mix its material with that of the egg, thus creating one cell -- the zygote. The egg activation steps are well known, but it is not yet clear which molecules initiate the activation process.
Richard Oko and colleagues report a new protein that appears to play a key role in the first stages of egg activation. They isolated the protein, called postacrosomal sheath WW domain-binding protein (PAWP), from several animal species and investigated its role in fertilization. They blocked PAWP from functioning in sperm cells and then injected them in eggs with a common in vitro fertilization technique called intracytoplasmic sperm injection. Without PAWP, the sperm cells were unable to activate the eggs, confirming the protein's role in initiating the activation process. The scientists also located PAWP to the region of the sperm cell's head already known to be involved in egg activation.
Article: "PAWP, a Sperm-specific WW Domain-binding Protein, Promotes Meiotic Resumption and Pronuclear Development during Fertilization" by Alexander T. H. Wu, Peter Sutovsky, Gaurishankar Manandhar, Wei Xu, Mika Katayama, Billy N. Day, Kwang-Wook Park, Young-Joo Yi, Yan Wei Xi, Randall S. Prather, and Richard Oko This article was featured as a "Paper of the Week" by the Journal of Biological Chemistry's Editors, meaning that it belongs to the top one percent of papers reviewed in significance and overall importance.
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