Forms I, II, and III are catalytically competent, while members of form IV lack Rubisco activity and play other roles in metabolism.

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Principal signaling receptor is Frizzled (Fz), contains 

7 TM α helices.

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

The palmitoleate attached to the Wnt protein binds to a specific site on the Fz extracellular domain and stabilizes the Wnt-Fz complex.

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Wnt signal transduction pathways classify into:

1. Canonical wnt pathway (β-catenin dependent)

2. Noncanonical wnt pathways (β-catenin independent)

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Noncanonical pathways can be divided into two types: 

1. The “planar cell polarity” pathway

2. The “Wnt/calcium” pathway

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Central player in the canonical Wnt pathway is β-catenin

TLS Online TPP Program

#Id: 9967

#Unit 4. Cell Communication and Cell Signaling

Homologs

β-catenin in vertebrates = Armadillo in Drosophila