Fig. 1. The actin-integrin linkage. The linkage between the extracellular matrix (ECM, red strand on top) and the actin cytoskeleton (represented by yellow beaded coils) is depicted. Integrins (represented by the - and β-transmembrane subunits in light blue and pink) can bind directly to the talin head domain (red sphere). Through its tail domain (red rod), talin can bind directly to actin as well as to other components of the linkage, such as vinculin (shown in purple). Vinculin can also bind to actin directly, as well as to the actin cross-linker -actinin (shown as a dimer, in green). Both vinculin and -actinin are anchored to the membrane, and their activity is modulated by interactions with phosphatidylinositol (4,5)-bisphosphate (PIP2). Finally, vinculin and FAK (shown in blue) can bind to the actin nucleator Arp2/3 (shown as a heptamer in grey).