RNA polymerases I or III do not have a CTD so no capping is stimulated

TLS Online TPP Program

#Id: 9626

#Unit 4. Cell Communication and Cell Signaling

Following binding of an EGF ligand, the rate of endocytosis of HER1 is increased about tenfold, and only a fraction of the internalized receptors return to the plasma membrane; the rest are degraded in lysosomes.

TLS Online TPP Program

#Id: 9627

#Unit 4. Cell Communication and Cell Signaling

Monoubiquitinylation of the HER1 cytosolic domain by the E3 ubiquitin ligase c-Cbl

TLS Online TPP Program

#Id: 9628

#Unit 4. Cell Communication and Cell Signaling

c-Cbl 

adds a single ubiquitin to a given lysine of a protein

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