Читать книгу Introduction to the Human Cell - Danton PhD O'Day - Страница 25

Adherens junctions are mainly found in epithelial cells where they lie just below tight junctions. Cadherins are the central proteins found in these junctions. As with other cadherins involved in cell adhesion, these proteins bind to ß-catenins in the cytoplasm which in turn associate with vinculin. These proteins are involved in binding to actin filaments. Thus there is a direct link between adherens junctions and the cytoskeleton. These junctions are most often organized as a “belt” that surrounds the complete cell.

Figure 3.8. The structure of an adherens junction.

Adherens junctions are important in keeping endothelial cells tightly bound as well. In blood vessels the tight association between endothelial cells maintains blood vessel integrity, keeping tissue cells out and blood cells contained within the blood vessel. The current view of adherens junctions is shown in Figure 3.8. Vinculin plays a key role in maintaining the tight association between endothelial cells and significant changes occur in the association of vinculin and actin in various diseases such as atherosclerosis and during cancer metastasis. The interplay between vinculin and actin as well as issues of metastasis are all covered in later chapters. The above and the following image show the homotypic binding between cadherins of two cells joined by an adherens junction. The alpha- and beta-catenins and vinculin mediate interaction with the actin cytoskeleton (Figure 3.9).

Figure 3.9. A diagram of the organization of adherens junction proteins.