In animal cells, the extracellular matrix allows cells within tissues to withstand external stresses and transmits signals from the outside of the cell to the inside. The extracellular matrix is extensive, and its composition varies between different types of tissues. For example, the reticular fibers and ground substance make up the ECM in loose connective tissue, while collagen and bone minerals make up the ECM of bone tissue.
Anchoring junctions mechanically attach a cell to the extracellular matrix or other cells. A cluster of anchoring junctions forms macromolecular complexes called focal adhesions or FAs. FAs regulate cell adhesion and mechanotransduction, which is the conversion of mechanical signals to chemical signals in the cell. FAs commonly occur on the lateral and basal surfaces of cells, providing strong and flexible connections. They were first recognized using an antitumor serum in Rous sarcoma virus-transformed rat kidney cells. Three proteins, talin, vinculin, and tensin, and their isoforms, link integrins to the cytoskeleton, thus strengthening the junction. Tension-dependent conformational changes activate talin and vinculin, thus suggesting their involvement in mechanosensing signals from their environment.
Adapted from section 4.2 Epithelial tissue- Anatomy and Physiology 2 e, Openstax
