Oolemmal proteomics

Abstract

Fertilization is defined as a series of gametic interactions in which capacitated sperm must first penetrate the egg vestments and then bind to and fuse with the egg plasma membrane (oolemma). The molecular basis of sperm–egg binding and fusion has yet to be elucidated due, in part, to how little is known about the array of proteins residing on the oolemma. Proteomics is an emerging area of research that directly evaluates protein expression by resolving, identifying, quantitating, and characterizing proteins utilizing a variety of techniques including high resolution two-dimensional polyacrylamide gel electrophoresis (2D PAGE), tandem mass spectrometry, and computer analysis. Our research group has utilized 2D PAGE to begin building a mouse oocyte proteomic database, with over 500 silver-stained proteins being resolved and digitized to date. Cell-surface labeling with biotin has identified a subset of 80 putative egg surface proteins. Amino acid microsequences from over 30 of the surface-labeled proteins has been obtained by tandem mass spectrometry. Sequences from eight of these proteins do not match any sequences from protein and DNA databanks, indicating that these proteins are novel. Our major current research goal is to clone, characterize, and express the novel proteins that are shown to be ovary-specific and investigate their functional roles in sperm–egg interaction.