Focused Proteomics on Egg Membrane Microdomains to Elucidate the Cellular and Molecular Mechanisms of Fertilization in the African Clawed Frog Xenopus laevis

Abstract

Involvement of protein tyrosine kinase-dependent signal transduction (PTK signaling) in fertilization was initially demonstrated by studies using sea invertebrates: namely, an increase of tyrosine phosphorylation in egg or embryo proteins is shown to occur within minutes after gamete interaction. Among vertebrate species so far studied are fi sh, frog, and some mammalian species in which the importance of PTK signaling for fertilization or activation of development has been shown. In this review chapter, we summarize our experimental data that explore the role played by the tyrosine kinase Src in fertilization of the African clawed frog Xenopus laevis . In addition, we introduce our recent approaches that focus on the structure and function of egg membrane microdomains (MDs), where the Src PTK signaling machinery is organized. Finally, we propose a hypothesis that gamete membrane interaction at fertilization is accompanied by mutual signaling cross-talk between egg and sperm using the egg MDs as scaffolds and discuss the versatility of our hypothesis in general understanding of the sexual reproduction mechanism.