Close inbreeding is harmful because it increases the proportion of homozygotes and thereby boosts the probability that deleterious and lethal recessive alleles.

TLS Online TPP Program

#Id: 9970

#XL - T Zoology

In the absence of Wnts,

“free” β-catenin are targeted for degradation by a cytosolic destruction complex that is held together by the tumor suppressor protein Axin.

TLS Online TPP Program

#Id: 9971

#XL - T Zoology

β-catenin Destruction Complex contains:

Tumor suppressor APC

Dvl protein

Constitutively active protein kinases GSK 3β and CK1

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