Sperm Surface Proteomics

Abstract

This contribution will focus exclusively on the total (global) protein composition (the proteome) of the sperm surface. Immune responses directed towards sperm surface proteins may cause infertility since functionally intact sperm are under immune attack. The immune attack can be achieved directly by deteriorating sperm or by antibody blocking of a sperm surface protein with a specific function in the fertilization process. Antibodies that bind to the sperm surface proteins could also impair the fertilization potential of sperm more indirectly by causing lateral redistribution of the sperm surface proteins and/or by hindrance of the assemblage of functional membrane protein complexes involved in fertilization. Currently the information about the sperm plasma membrane proteome is increasing but has only led to limited understanding of the functionality that is related to the complex ordering and processing of this specific cell surface. New proteomic data and new strategies designed for complete coverage of the surface proteome of mammalian sperm will significantly increase our understanding of how fertilization is accomplished but also how immune responses may frustrate this process. This information will become highly relevant for studying immune infertility. An overview is provided about the current knowledge of the sperm surface and how this structure should experimentally be approached for proteomic studies. Comparative analysis of different mammalian species is covered as this will provide better understanding for the possibilities and limitations of analyzing the surface proteome of human sperm.