Describe the elements of a focal adhesion and what their rol

Describe the elements of a focal adhesion and what their role is in transmitting extracellular signals to the intracellular environment.

Solution

Elements of focal adhesion:

Connection between the extra-cellular matrix and intracellular environment is established by the integrins that bind to the ECM via fibronectin and other ECM-associated proteins like collagen, laminin, vitronectin and thrombospondin. The intracellular domains of the integrins is linked to actin fibers by anchor proteins including talin, alpha-actinin, filamin and vinculin.

Role in transmitting extracellular signals to the intracellular environment:

Actin filament : It is links ECM focal contacts (integrin) to the sytoskeleton, via anchor proteins - talin, alpha-actinin, vinculin.

Alpha-actinin : Anchor protein, serves as ligand for integrins and supports integrin-mediated cell adhesion.

Vinculin : Anchor protein, serves as ligand for integrins and supports integrin-mediated cell adhesion.

Talin : It regulates integrin binding to actin, serves as ligand for integrins and supports integrin-mediated cell adhesion.

Integrin : As transmembrane adhesion receptor, binds to protein components of the ECM.

Fibronectin : It serves as major adhesion molecule and links cells to collagen and proteoglycans. Changes in organization of fibronectin impacts integrin signaling.

Filamin : It promotes inactive conformation of integrins and is a negative regulator of ligand binding.