קטנינים

Catenins are a diverse group of adapter proteins that participate in cell-cell adhesion.

Catenins have multiple binding domains that bind cadherins, cytoskeletal components, and various cytoskeletal regulator proteins. Thus, they link the cytoskeleton with cadherins at the cell adhesion sites.

While some catenins, such as plakoglobin and plakophilin, help establish stable connections between cadherins and the intermediate filaments,others, such as alpha- and beta-catenins, dynamically organize the actin cytoskeleton at the plasma membrane.

The organization of actin filaments begins with the binding of beta-catenin to the cytosolic domain of a cadherin molecule. Following this, alpha-catenin binds to the beta-catenin.

Another catenin, p120, also tethers to these complexes and regulates the stability of cadherins on the membrane.

As a few cadherin-catenin complexes cluster together, the alpha-catenins dissociate and form cytosolic dimers.

These alpha-catenin dimers interact strongly with the filamentous actin and help organize actin bundles, thus providing cytoskeletal strength to the cell adhesion sites.