The addition of the 3’-CCA is catalyzed by the enzyme tRNA nucleotidyltransferase, which functions as a nontemplate-directed RNA polymerase.

TLS Online TPP Program

#Id: 9343

#Unit 4. Cell Communication and Cell Signaling

Prodomain forms disulfide linkages that localize the latent TGF-β to the surface of the secreting cell (GARP), to a nearby cell, or to the extracellular matrix (LTBP).

TLS Online TPP Program

#Id: 9345

#Unit 4. Cell Communication and Cell Signaling

TGF-β activation

By cytoskeletal force transmitted by integrins

TLS Online TPP Program

#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.

TLS Online TPP Program

#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

TLS Online TPP Program

#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)