Affinity modulation of platelet integrin alpha(sub IIb)beta3 by beta3-endonexin, a selective binding partner of the beta3 integrin cytoplasmic tail

A novel 111-amino acid polypeptide called beta3-endoxin was recently identified through the utilization of a yeast two-hybrid screening strategy. The polypeptide can be fused to the cytoplasmic tail of the beta3 integrin subunit in both yeast and in vitro, but it cannot bind to other integrin tails such as beta1, beta2, and alpha(sub IIb). The Chinese hamster ovary cell model system was used to express alpha(sub IIb)beta3 and beta3-endoxin, showing the protein's ability to strengthen the affinity state and adhesive function of alpha(sub IIb)beta3.