Catenin

Catenins (from the Latin ' catena ' for chain ) are a group of proteins that were first described as a link between cell adhesion molecules and the proteins Zellcytoskelett in certain cell-cell connections, the adherens junctions. Means that they form a functional group that have been designated by Greek letters. In the classical cadherin -catenin complex connect β -catenin and α -catenin, a cadherin molecule to the actin cytoskeleton. In addition to this involvement in cell adhesion has now been shown that at least β -catenin is also involved in a signal transduction pathway, the Wnt signaling pathway.

α -catenin

α -catenin does not have any similarity to β -catenin and both forms homodimers as well as a heterodimer with β -catenin. It can also bind actin filaments. About the connection of this Zelladhäsionskomplexes other proteins is mediated by the cytoskeleton of the cell. This compound is highly regulated, so that connections between the cells remain flexible, which is especially during the development of the organism is important when cells and cell layers are still subject to strong cell migration processes. This anchoring has been described with the cytoskeleton for different cadherins. The defect of α -catenin leads among other things to interfere with the formation of synapses.

β -catenin

β -catenin binds to the cytoplasmic part of cadherins ( the catenin binding domain ) and thus forms a bridge between cadherin and α -catenin. Related is β -catenin with plakoglobin. β -catenin also serves as a signaling molecule in the Wnt signaling pathway. It is in this case transported into the nucleus and acts there as a component of a transcription factor. This is presumably the cause of increased β -catenin levels in certain cancers. Mutations in the gene lead to hereditary CTNNB adenomas and tumors.

More catenins

Similar to β -catenin also acts γ -catenin and δ -catenin ( p120 ). The latter also acts as a substrate for specific kinases in other signal transduction pathways (for example, EGF, etc.).