All DNA polymerases require a 3'-0H priming end to initiate DNA synthesis.

TLS Online TPP Program

#Id: 9629

#Unit 4. Cell Communication and Cell Signaling

c-Cbl contains: 

a domain that binds directly to phosphorylated EGF receptors

a RING finger domain, which recruits ubiquitin-conjugating enzymes and mediates transfer of ubiquitin to the receptor

TLS Online TPP Program

#Id: 9630

#Unit 4. Cell Communication and Cell Signaling

Other EGF family receptors HER2, HER3, and HER4 do not undergo internalization after exposure to ligand

TLS Online TPP Program

#Id: 9631

#Unit 4. Cell Communication and Cell Signaling

Monomeric Ras protein 

(∼170 amino acids) belongs to the GTPase superfamily of

intracellular switch proteins

TLS Online TPP Program

#Id: 9632

#Unit 4. Cell Communication and Cell Signaling

Ras has an intrinsically slower rate of GTP hydrolysis, so Ras∙GTP requires the assistance of another protein, GAP.

TLS Online TPP Program

#Id: 9633

#Unit 4. Cell Communication and Cell Signaling

Binding of a GAP to Ras⋅GTP accelerates the intrinsic GTPase activity of Ras by more than a hundredfold

TLS Online TPP Program

#Id: 9634

#Unit 4. Cell Communication and Cell Signaling

The GAP for RAS (called a RAS-GAP) works by inserting one of its arginine side chains into the Ras active site, thus stabilizing an intermediate in the

hydrolysis reaction.