Do fertilin beta and cyritestin play a major role in mammalian sperm-oolemma interactions? A critical re-evaluation of the use of peptide mimics in identifying specific oocyte recognition proteins

Integrins have been proposed to play a role in mammalian sperm-oocyte interactions for many years. To a large extent this hypothesis stems from the ability of short synthetic peptides, based on the disintegrin-like domains of two sperm surface integral membrane proteins, fertilin beta and cyritestin, to inhibit sperm--oocyte binding and fusion in vitro. Here we argue that such peptide mimics lack specificity in these simple IVF assay systems. Hence, whilst not precluding a role for fertilin beta and cyritestin in sperm-oolemma interactions, this lack of specificity indicates the need for considerable caution when interpreting results obtained using this approach.