Final answer:
Experiments have shown that most integrins have unique functions. Integrins respond to fibronectin, signaling cell and tissue differentiation. Focal adhesions play a crucial role in connecting integrins to the cytoskeleton.
Step-by-step explanation:
Experiments have provided evidence that most integrins have unique functions. For example, Deshpande and coworkers developed a computational approach that showed the coexistence of both low and high affinity integrins in thermodynamic equilibrium. They also demonstrated the mechanical equilibrium of the contractile forces generated by stress fibers, which affect the free energies of the integrins.
Another study focused on cell adhesion found that integrins respond to fibronectin by signaling cell and tissue differentiation. This study also showed that integrin adhesion receptors bind to proteins within the extracellular matrix, such as fibronectin, laminin, and collagens.
In addition, research on focal adhesions revealed that the transmembrane adhesion receptors of the integrin family consist of two subunits with relatively large headpieces that bind to the matrix and relatively small cytoplasmic tails. Proteins like talin, vinculin, and paxillin crosslink neighboring integrins, connecting them to the actin cytoskeleton.