Final answer:
Integrins are cell adhesion molecules that bind to extracellular matrix proteins, particularly collagen, fibronectin, and laminin. They are transmembrane receptors that help cells adhere to the ECM, and they are influenced by the mechanics of cell adhesion, involving the actin cytoskeleton's contractile forces.
Step-by-step explanation:
Integrins are a type of cell adhesion molecule that play a critical role in connecting cells to the extracellular matrix (ECM). They are transmembrane receptors that facilitate cell-ECM adhesion. According to the question, integrins bind to several molecules but among the provided options, the correct answer is extracellular matrix proteins such as collagen. When integrins bind to the ECM, they do so through their extracellular domains, connecting to proteins like collagen, which is a major component of the ECM.
Fibronectin, another glycoprotein component of the ECM, also binds to integrins and plays an important role in cell adhesion and migration. Within the plasma membrane, low and high affinity integrins coexist, and their distribution is significantly influenced by the contractile forces exerted by the actin cytoskeleton, affecting integrin's free energies and contributing to cell adhesion mechanics.
Therefore, among the options provided in the student's question, none specifically describe the primary ligands for integrins. Instead, integrins primarily bind to proteins like collagen, fibronectin, and laminin within the ECM.