PROACROSIN AND ACROSIN - A MULTIFUNCTIONA L COMPLEX IN RETRO SPECT

Proacrosin is a molecule that is located under the acrosomal cap and t hat acts as a secundary ligand after acrosome reaction. Proacrosin is thought to bind to ZP2 (zona pellucida receptor 2). The high affinity is based on the interaction of the zona pellucida glycoprotein's acidi c sulphate groups with basic, positively charged amino acids of the pr oacrosin molecule. Proacrosin is a serin protease and is capable to ly se the zona pellucida locally. Our structural analysis of proacrosin s hows, that the catalytic centre is surrounded by loops containing posi tively charged amino acids which create the binding domain. This revie w is intended to describe the results that lead to the elucidation of the biochemistry or proacrosin.