beta Catenin

β-Catenin was a cytosolic protein originally identified through its association with the cadherin class of celladhesion proteins. β-Catenin has two key cellular functions; one plays direct role in cell adhesion, bridging between cadherins and the actin cytoskeleton. The other plays as a transcription cofactor with T cell factor/lymphoid enhancer factor(TCF/LEF) in the Wnt pathway. Glycogen synthase- 3β(GSK3β) may destabilize β-Catenin by phosphorylation at Ser33/37 and thr41. A complex of axin and casein kinase I(CKI) induces β-catenin phosphorylation at a single site: serine 45(S45). S45 phosphorylation is necessary and sufficient to mobilize a GSK3β mediated cascade. Mutation of these phosphorylation sites in β- Catenin have been found in many tumor cell lines.