HER3 lacks a functional kinase domain

TLS Online TPP Program

#Id: 9972

#XL - T Zoology

Kinases CK1 and GSK3,

sequentially phosphorylate β-catenin at multiple serine and threonine residues

TLS Online TPP Program

#Id: 9973

#XL - T Zoology

E3 βTrCP ubiquitin ligase then binds to two phosphorylated residues on β catenin, leading to ubiquitinylation and degradation in proteasomes.

TLS Online TPP Program

#Id: 9974

#XL - T Zoology

In the absence of Wnt,

TCF is associated with transcriptional repressor proteins Groucho (Gro) that inhibit gene transcription in nucleus

TLS Online TPP Program

#Id: 9976

#XL - T Zoology

Formation of the Wnt/Fz/LRP complex at the cell

surface causes the adaptor protein Dishevelled, to bind to Fz and Axin to bind to LRP, resulting destabilization and inactivation of the destruction complex

TLS Online TPP Program

#Id: 9977

#XL - T Zoology

Unphosphorylated β-catenin translocates to the nucleus.

TLS Online TPP Program

#Id: 9978

#XL - T Zoology

β-catenin binds to TCF to displace the Gro repressor and recruits co-activator proteins Pygo, LGS, to activate target gene expression.