When blood glucose rises above 5 mM, hexokinase IV activity increases, but hexokinase I is already operating near Vmax and cannot respond to an increase in glucose concentration. 

TLS Online TPP Program

#Id: 9346

#XL - T Zoology

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

#XL - T Zoology

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

#XL - T Zoology

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

RI, RII, and RIII

TLS Online TPP Program

#Id: 9350

#XL - T Zoology

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)

TLS Online TPP Program

#Id: 9351

#XL - T Zoology

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

TLS Online TPP Program

#Id: 9352

#XL - T Zoology

RIII, also called β-glycan, is a cell-surface proteoglycan.