Beta-catenin

Beta-catenin is a protein that in humans is encoded by the CTNNB1 gene. This protein is part of a complex of proteins that constitute adherens junctions (AJs). AJs are necessary for the creation and maintenance of epithelial cell layers by regulating cell growth and adhesion between cells. Beta-catenin also anchors the actin cytoskeleton and may be responsible for transmitting the contact inhibition signal that causes cells to stop dividing once the epithelial sheet is complete.

Etymology

The term "beta-catenin" is derived from the Greek word "katenin" meaning "down" and the prefix "beta" indicating its position in the sequence of proteins identified in the catenin family.

Structure

Beta-catenin is a 781-amino acid protein that contains several functional domains: an N-terminal domain, a C-terminal domain, and a central regulatory domain. The N-terminal domain is involved in the regulation of beta-catenin stability. The C-terminal domain is involved in transactivation and interaction with other proteins. The central regulatory domain contains 12 imperfect repeats known as armadillo repeats.

Function

Beta-catenin has dual functions in the cell: cell-cell adhesion and gene transcription. In cell-cell adhesion, beta-catenin forms complexes with cadherin proteins and is linked to the actin cytoskeleton through alpha-catenin. In gene transcription, beta-catenin interacts with TCF/LEF transcription factors to activate the transcription of target genes.

Clinical significance

Mutations and overexpression of beta-catenin have been implicated in many cancers, including hepatocellular carcinoma, colorectal carcinoma, lung cancer, ovarian cancer, and endometrial cancer. Beta-catenin is also involved in the development of adenomas and the progression to adenocarcinomas in the colon.

See also

• Catenin
• Cadherin
• TCF/LEF
• Adenoma
• Adenocarcinoma

References

Beta-catenin Resources
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