Practice question

Canonical Wnt pathway depends strictly on beta-catenin as transcriptional coactivator linking membrane to nucleus. Wnt binding to Frizzled cysteine-rich domain and LRP5/6 co-receptor recruits Dishevelled scaffold polymerizing via DIX domain, disassembling destruction complex composed of Axin, APC, GSK3, CK1alpha. Stabilized beta-catenin accumulates cytosol, enters nucleus via importin, binds TCF/LEF replacing Groucho corepressor recruiting Legless to activate targets like c-Myc, Cyclin D1, Axin2. Non-canonical pathways include Planar Cell Polarity via Rho-JNK orienting hairs and convergent extension, and Calcium via PKC-CamKII antagonizing canonical. Discrimination underlies diverse Wnt functions.