INTEGRIN CYTOPLASMIC INTERACTIONS AND BIDIRECTIONAL TRANSMEMBRANE SIGNALING

Integrins are heterodimeric integral plasma membrane proteins containi ng extracellular, transmembrane, and cytoplasmic domains. These highly versatile receptors mediate not only cell adhesion and migration, but also the bidirectional transfer of information across the plasma memb rane. The cytoplasmic domains of integrins are required for the transd uction of this bidirectional information, and have recently been shown to participate in direct interactions with some novel cytoplasmic pro teins, such as an ankyrin repeat containing serine/threonine protein k inase (integrin-linked kinase) and beta(3) endonexin. New evidence als o suggests that, via interactions with focal adhesion kinase, the inte grin cytoplasmic domains can coordinate actin cytoskeletal organizatio n and responses to growth factors. The elucidation of the signal trans duction pathways activated by integrins is an intense area of investig ation that has shown that integrins have some unique properties as sig nal transducing receptors.