Under normal conditions, β catenin is kept at low levels in the cell through a destruction complex that includes proteins like adenomatous polyposis coli (APC), glycogen synthase kinase 3β (GSK-3β), and axin. This complex phosphorylates β catenin, marking it for ubiquitination and subsequent proteasomal degradation. When the pathway is activated by Wnt ligands binding to Frizzled receptors, the destruction complex is inhibited. This allows β catenin to accumulate in the cytoplasm and translocate into the nucleus, where it interacts with T-cell factor/lymphoid enhancer factor (TCF/LEF) transcription factors to regulate gene expression.
