Cadherins (named for "calcium-dependent adhesion") are cell adhesion molecules important in forming adherens junctions that let cells adhere to each other. Cadherins are a class of type-1 transmembrane proteins, and they depend on calcium (Ca2+) ions to function, hence their name. Cell-cell adhesion is mediated by extracellular cadherin domains, whereas the intracellular cytoplasmic tail associates with numerous adaptors and signaling proteins, collectively referred to as the cadherin adhesome. The cadherin family is essential in maintaining cell-cell contact and regulating cytoskeletal complexes. The cadherin superfamily includes cadherins, protocadherins, desmogleins, desmocollins, and more. In structure, they share cadherin repeats, which are the extracellular Ca2+-binding domains. There are multiple classes of cadherin molecules, each designated with a prefix for tissues with which it associates. Classical cadherins maintain the tone of tissues by forming a homodimer in cis while desmosomal cadherins are heterodimeric. The intracellular portion of classical cadherins interacts with a complex of proteins that allows connection to the actin cytoskeleton. Although classical cadherins take a role in cell layer formation and structure formation, desmosomal cadherins focus on resisting cell damage. Desmosomal cadherins maintain the function of desmosomes that is to overturn the mechanical stress of the tissues. Similar to classical cadherins, desmosomal cadherins have a single transmembrane domain, five EC repeats, and an intracellular domain. There are two types of desmosomal cadherins: desmogleins and desmocollins. These contain an intracellular anchor and cadherin like sequence (ICS). The adaptor proteins that associate with desmosomal cadherins are plakoglobin (related to -catenin), plakophilins (p120 catenin subfamily), and desmoplakins. The major function of desmoplakins is to bind to intermediate filament by interacting with plakoglobin, which attach to the ICS of desmogleins, desmocollins and plakophilins. Typical cadherins are different from other types of cadherins and consist of one or more extracellular repeat domains. The components that build an atypical cadherin are flamingo (seven pass transmembrane) and Dcad102F-like cadherins. They take part in signaling pathways instead of performing cell-cell adhesion. Cells containing a specific cadherin subtype tend to cluster together to the exclusion of other types, both in cell culture and during development. For example, cells containing N-cadherin tend to cluster with other N-cadherin-expressing cells. However, mixing speed in cell culture experiments can effect the extent of homotypic specificity. In addition, several groups have observed heterotypic binding affinity (i.e., binding of different types of cadherin together) in various assays. One current model proposes that cells distinguish cadherin subtypes based