In Xenopus, this pathway’s namesake proteins are secreted by the Nieuwkoop center. For 10 points each:
[10m] Name this family of conserved signaling pathways that is critical to cell proliferation during embryonic development. The canonical form of this pathway relies on the protein beta-catenin.
ANSWER: Wnt (“wint”) pathways
[10e] Each Wnt pathway begins with a Wnt ligand binding to Frizzled, one of these proteins. Proteins in this broad class of cell surface receptors have seven transmembrane helices.
ANSWER: G-protein-coupled receptors [or GPCRs; accept serpentine receptors or metabotropic receptors; accept G protein-linked receptors or GPLRs; prompt on heptahelical receptors]
[10h] In canonical Wnt signaling, this protein phosphorylates beta-catenin in the absence of Wnt proteins. Along with axin and APC, it forms a destruction complex that degrades beta-catenin.
ANSWER: GSK-3 [or glycogen synthase kinase 3; accept GSK-3 alpha or GSK-3 beta; prompt on glycogen synthase kinase or GSK; reject “glycogen synthase”]
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