Normally there are 20 AATS exclusively specific for specific amino acid.

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#Id: 7168

#Unit 5. Developmental Biology

Nieuwkoop center 

Dorsalmost vegetal cells of the blastula, which are capable of inducing the organizer dorsal vegetal cells can induce animal cells to become dorsal mesodermal tissue)

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#Id: 7169

#Unit 5. Developmental Biology

The major candidate for the factor that forms the Nieuwkoop center was β-catenin (This multifunctional protein also proved to be a key player in the formation of the dorsal amphibian tissues)

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#Id: 7170

#Unit 5. Developmental Biology

During first cleavage, GBP, Dsh, and Wnt11 are brought into the future dorsal section of the embryo protect β-catenin

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#Id: 7171

#Unit 5. Developmental Biology

During cleavage, β-catenin enters the nuclei and binds with Tcf3 to form a transcription factor that activates genes encoding proteins Siamois and Twin.

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#Id: 7172

#Unit 5. Developmental Biology

Siamois and Twin interact in the organizer with the Smad2 transcription factor activated by vegetal TGF-β family members (Nodal-related proteins, Vg1, activin)

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#Id: 7173

#Unit 5. Developmental Biology

Twin and Siamois encode homeodomain transcription factors and are expressed in the organizer