DYNAMIC ASPECTS OF ADHESION RECEPTOR FUNCTION - INTEGRINS BOTH TWIST AND SHOUT

The recognition of extracellular molecules by cell surface receptors i s the principal mechanism used by cells to sense their environment. Co nsequently, signals transduced as a result of these interactions make a major contribution to the regulation of cellular phenotype. Historic ally, particular emphasis has been placed on elucidating the intracell ular consequences of growth factor and cytokine binding to cells. In a ddition to these interactions, however, cells are usually in intimate contact with a further source of complex structural and functional inf ormation, namely immobilised extracellular matrix and/or cell surface adhesion proteins. A key question in recent years has been whether cel ls use the myriad of adhesion protein-receptor interactions purely for structural and migratory function, or whether these interactions also make a more varied contribution to cell phenotype. Here we review dyn amic aspects of the function of one major class of adhesion receptor, the integrins. In particular, we focus on the evidence for shape chang es in integrin molecules, the mechanisms responsible for regulating li gand binding, and the signals transduced following integrin occupancy.