Catenins
Catenins (from the Latin 'catena' for chain) are a group of proteins that were first described as connecting proteins between cell adhesion molecules and the cell cytoskeleton in certain cell-cell connections , the adherens junctions . They form a functional group that was named with Greek letters. In the classic cadherin -catenin complex, β-catenin and α-catenin combine a cadherin molecule with the actin cytoskeleton . In addition to this involvement in cell adhesion , it has now been shown that at least β-catenin is also involved in a signal transduction pathway , the Wnt signal pathway .
α-catenin
α-catenin bears no resemblance to β-catenin and forms both homodimers and a heterodimer with β-catenin. It can also bind actin filaments . The connection of this cell adhesion complex to the cytoskeleton of the cell is mediated via further proteins . This connection can be highly regulated so that connections between the cells remain flexible, which is particularly important during the development of the organism, when cells and cell layers are still subject to strong cell migration processes . This anchoring with the cytoskeleton was described for various cadherins . The defect in α-catenin leads, among other things, to disturbances in the formation of synapses .
β-catenin
β-catenin binds to the cytoplasmic part of cadherins (to the catenin-binding domain) and thus forms a bridge between cadherin and α-catenin. Β-catenin is related to plakoglobin . β-catenin also serves as a signaling molecule in the Wnt signaling pathway . It is transported into the cell nucleus and acts there as a component of a transcription factor . This is probably also the cause of increased β-catenin concentrations in certain tumors . Mutations in the CTNNB gene lead to hereditary adenomas and tumors.
More catenins
Similar to β-catenin, γ-catenin ( plakoglobin ) and δ-catenin ( p120 ) also have an effect . The latter also acts as a substrate for certain kinases in other signal transduction pathways (e.g. EGF and others).
literature
- Bruce Alberts et al: Molecular Biology of the Cell. 4th edition. Garland Science, New York NY 2002, ISBN 0-8153-4072-9 .