Jasplakinolide,

a sponge toxin, enhances nucleation by binding and stabilizing actin dimers and lowering the Cc.

TLS Online TPP Program

#Id: 9355

#XL - T Zoology

Most cells lack RIII, TGF-β binds directly to the RII

dimer, but Active RII kinase activity is not sufficient to generate an intracellular signal

TLS Online TPP Program

#Id: 9356

#XL - T Zoology

RI will not bind to RII unless RII is bound to TGF-β.

TLS Online TPP Program

#Id: 9357

#XL - T Zoology

RII phosphorylates serine and threonine in the juxtamembrane segment of the RI (ligand induced receptor hetero-oligomerization), releasing the inhibition of RI kinase activity.

TLS Online TPP Program

#Id: 9358

#XL - T Zoology

Active type I receptor kinase phosphorylates a Smad

TLS Online TPP Program

#Id: 9359

#XL - T Zoology

Three types of Smad proteins function in the TGF-β signaling pathway: 

R-Smads (Smad2 and Smad3)

Co-Smads (Smad4)

I-Smads (Smad7)

TLS Online TPP Program

#Id: 9360

#XL - T Zoology

Smad2/3 become phosphorylated by active RI receptors and together with Smad4 move into the nucleus to activate gene transcription