Final answer:
Talin activates inside-out signaling through integrin by binding to its cytoplasmic tails, leading to a conformational change which increases integrin's affinity for the ECM. This promotes the formation of focal adhesions and initiates downstream signaling pathways.
Step-by-step explanation:
Talin plays a critical role in activating inside-out signaling through integrin by linking integrins to the actin cytoskeleton, and thereby modulating their affinity for ligands. In the resting state, integrins exhibit low affinity for their ligands and are somewhat inactive. However, when talin binds to the cytoplasmic tails of integrin subunits, it induces a conformational change that increases the affinity of the integrin for its extracellular matrix ligands, such as collagen. This binding is crucial for the subsequent recruitment and clustering of integrins at focal adhesions, where additional structural and signaling proteins, like vinculin and paxillin, are recruited to further strengthen the link between the integrins and the actin cytoskeleton.
The result of talin-mediated activation of integrins is a robust attachment of cells to the extracellular matrix and the initiation of downstream signaling pathways which can lead to changes like cell migration, survival, and differentiation. Tyrosine phosphorylation of proteins involved in downstream signaling cascades is a common mechanism by which engagement of integrins leads to cellular responses.