Sperm membrane physiology and relevance for fertilization.

This paper aims to overview recent insights in sperm surface remodelling pertinent to fertilization. A basic understanding of this remodelling is required to interpret the high amount of data appearing from high-throughput identification techniques for proteins presently applied in reproductive biology. From the extensive lists of protein candidates identified by proteomics, only a few are recognized to be directly involved in fertilization. Others are indirectly involved, but many are not yet considered to be involved in fertilization. Some of these newly identified and unexpected proteins may shed new light in the current molecular models for fertilization. However, the gathered lists of sperm proteins possibly involved in fertilization do only tell a part of the story regarding how fertilization is accomplished. When considering the identification of proteins involved in fertilization, one also needs to take into account the fundamental mechanisms involved in the redistribution of sperm surface proteins in membrane protein complexes and the involvement of cell signalling events that regulate their post-translational modification status. Both processes are likely requisite for protein configuration and grouping into functional membrane protein complexes necessary to elicit their delicate roles in fertilization. This paper emphasizes biochemical models for membrane surface modelling and their potential involvement for remodelling the sperm surface in the above described processes.