In their "canonical" pathway
the Wnt proteins activate 2
membrane receptors :
- LRP, which activates an Axin,
GSK3, APC complex, which activates
b catenin
b Catenin once activated, translocates to the nucleus, moves Groucho from its binding to TCF and becomes a target gene transcription activator
- Fz (frizzled) which activates Disheveled (Dvl)
which in turn activates Axin/GSK3/APC, and
b catenin
2 inhibitors control the system :
- DKK (Dickkopf) which binds to LRP
- WIF (Wnt inhibitor factor) which binds to Wnt
Stem cell
Non-canonical pathways :
- Wnt can induce stem cell expansion
- Wnt, through RYK , acts on axonal guidance
The Wnt pathways
Abbreviations :

APC adenomatous polyposis coli, c-Met mesenchymal epithelial transition receptor, DKK Dickkopf, Dvl disheveled, Fz frizzled, GSK glycogen synthase kinase, HGF hepatocyte growth factor, LDRP low density lipoprotein receptor protein, OPG osteoprotegerin, RYK receptor related to tyrosine kinase, RANK-L receptor activator of nuclear factor kappa B-ligand, TCF T-cell specific transcription factor, WIF, Wnt inhibitor factor, Wnt wingless
A completely different system, the HGF/c-MET system can also activate beta catenin.