THE MOLECULAR ARCHITECTURE OF FOCAL ADHESIONS

This article outlines the present knowledge of the architecture, molec ular composition, and dynamics of focal contacts of adhesive animal ce lls. These structures, developed at the plasma membrane at sites where cells touch their substratum, are essential for cellular attachment i n tissue formation during embryogenesis and wound healing. In tissue c ulture, they are particularly prominent and thus amenable to detailed investigation. Focal contacts consist of a cytoplasmic face, comprisin g cytoskeletal elements, a transmembrane connecting region, and an ext racellular face composed of proteins of the extracellular matrix. The molecular anatomy of the numerous proteins involved, the basis for cla ssifying them as structural or regulatory components, and their in vit ro interactions are described. Based on this information, current mode ls on the dynamics of their assembly and of possible regulatory mechan isms involving a variety of signal transduction pathways are discussed .