Question

Beta-Catenin is the transcription factor that mediates Wnt signaling. What would facilitate the destabilization of beta-catenin in the absence of Wnt signal?

(a) BRCA1
(b) PTEN
(c) Rb
(d) APC

Answer 1

The destabilization of beta-catenin in the absence of Wnt signal is facilitated by the protein APC (Adenomatous Polyposis Coli). Therefore, the correct option is APC. Therefore, the correct option is D.

Step-by-step explanation:

APC is an essential component of the destruction complex, a cellular apparatus that controls beta-catenin levels. When Wnt signalling is not present, the destruction complex—which consists of APC, Axin, glycogen synthase kinase 3 (GSK-3), and casein kinase 1 (CK1)—targets beta-catenin for degradation.

Beta-catenin is phosphorylated by the destruction complex, which marks it for ubiquitination and proteasome degradation. By doing this, the unintended activation of target genes by Wnt signalling is prevented and beta-catenin levels remain low.

Therefore, the correct option is D.