Cytoskeletal protein radixin activates integrin α Mβ 2 by binding to its cytoplasmic tail

Abstract

Talin binding of integrins, via its band 4.1, ezrin, radixin, and moesin (FERM)-homologous domain, directly activates the integrin receptor. However, it is not known whether other FERM-containing proteins also possess such an integrin activating capability. We report here that radixin, one of the original FERM-domain proteins, binds to the membrane-proximal region of the integrin β 2 but not α M cytoplasmic tail. Importantly, we show that radixin binding significantly enhances the adhesive activity of integrin α Mβ 2. Given the distinct biological activities of radixin and talin, radixin may represent a novel talin-independent pathway for integrin activation under specific settings.