Caténine

Catenins are a family of proteins found in complexes with cadherin cell adhesion molecules of animal cells. The first two catenins that were identified became known as α-catenin and β-catenin. α-Catenin can bind to β-catenin and can also bind filamentous actin (F-actin). β-Catenin binds directly to the cytoplasmic tail of classical cadherins. Additional catenins such as γ-catenin and δ-catenin have been identified. The name "catenin" was originally selected ('catena' means 'chain' in Latin) because it was suspected that catenins might link cadherins to the cytoskeleton. α-catenin β-catenin γ-catenin δ-catenin All but α-catenin contain armadillo repeats. They exhibit a high degree of protein dynamics, alone or in complex. Several types of catenins work with N-cadherins to play an important role in learning and memory. Cell-cell adhesion complexes are required for simple epithelia in higher organisms to maintain structure, function and polarity. These complexes, which help regulate cell growth in addition to creating and maintaining epithelial layers, are known as adherens junctions and they typically include at least cadherin, β-catenin, and α-catenin. Catenins play roles in cellular organization and polarity long before the development and incorporation of Wnt signaling pathways and cadherins. The primary mechanical role of catenins is to connect cadherins to actin filaments, such as the adhesion junctions of epithelial cells. Most studies investigating catenin actions have focused on α-catenin and β-catenin. β-catenin is particularly interesting as it plays a dual role in the cell. First of all, by binding to cadherin receptor intracellular cytoplasmic tail domains, it can act as an integral component of a protein complex in adherens junctions that helps cells maintain epithelial layers. β-catenin acts by anchoring the actin cytoskeleton to the junctions, and may possibly aid in contact inhibition signaling within the cell.