LexA repressor (Mr 22,700) inhibits transcription of all the SOS genes, and induction of the SOS response requires removal of LexA

TLS Online TPP Program

#Id: 9337

#Unit 4. Cell Communication and Cell Signaling

Principal function of all 3 human TGF-β isoforms, TGF-β1, 2, and 3:

Prevent cell proliferation by inducing the synthesis of p15 INK4B

TLS Online TPP Program

#Id: 9338

#Unit 4. Cell Communication and Cell Signaling

Monomeric active forms of all members of the TGF-β family (3 conserved intramolecular disulfide Linkages) contain a conserved cysteine residue that forms a disulfide bond links TGF-β monomers into functional homodimers

and heterodimers

TLS Online TPP Program

#Id: 9339

#Unit 4. Cell Communication and Cell Signaling

TGF-β is synthesized with a, 

250-residue N-terminal prodomain

∼110-residue C-terminal TGF-β domain

TLS Online TPP Program

#Id: 9340

#Unit 4. Cell Communication and Cell Signaling

N-terminal prodomain is required for proper folding and dimerization of the C-terminal TGF-β domain.

TLS Online TPP Program

#Id: 9341

#Unit 4. Cell Communication and Cell Signaling

TGF-β latency

In the Golgi prodomain is proteolytically cleaved from the mature growth factor but remains noncovalently attached even after secretion.

TLS Online TPP Program

#Id: 9342

#Unit 4. Cell Communication and Cell Signaling

Prodomain prevents the latent TGF-β 

from binding to a cell-surface receptor.