Replacement of Pyrimidine to Purine or vice versa is called Transversion.

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#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

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#Unit 4. Cell Communication and Cell Signaling

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

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#Unit 4. Cell Communication and Cell Signaling

Monomeric Ras protein 

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

intracellular switch proteins

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#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.

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#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

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#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.