Cytokinins are defined as compounds that have biological activities similar to those of trans-zeatin.

TLS Online TPP Program

#Id: 9345

#Unit 4. Cell Communication and Cell Signaling

TGF-β activation

By cytoskeletal force transmitted by integrins

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#Id: 9346

#Unit 4. Cell Communication and Cell Signaling

The prodomains of TGF-β1 and TGF-β3 contain a RGD motif, that allows them to bind to integrins.

TLS Online TPP Program

#Id: 9347

#Unit 4. Cell Communication and Cell Signaling

During cell migration, a tensile force is generated which physically distorts the prodomain and frees the active TGF-β dimer, initiating TGF-β signaling.

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#Id: 9348

#Unit 4. Cell Communication and Cell Signaling

3 separate TGF-β receptor proteins participate in binding TGF-β and activating signaling:

RI, RII, and RIII

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#Id: 9350

#Unit 4. Cell Communication and Cell Signaling

RI and RII receptors are homodimeric proteins with serine/threonine kinases in their cytosolic domains. 

(RI and RII sufficient to serve as a functional hetero-tetrameric TGF-β receptor)

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#Id: 9351

#Unit 4. Cell Communication and Cell Signaling

RII exhibits constitutive kinase activity; means it is active even when not bound to TGF-β.