The third base of each codon plays a lesser role in specifying an amino acid than the first two.

TLS Online TPP Program

#Id: 9644

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 9645

#Unit 4. Cell Communication and Cell Signaling

Active Ras⋅GTP binds to the N-terminal autoinhibitory domain of Raf, altering its conformation and allowing the phosphate attached to this domain to be removed by cytosolic phosphatases, causing loss of 14-3-3 binding.

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Active Raf phosphorylates MEK on one or two serine residues in its activation loop, activating MEK kinase activity

TLS Online TPP Program

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#Unit 4. Cell Communication and Cell Signaling

Constitutively active Raf kinase

a glutamic acid substitution for the valine at position 600

TLS Online TPP Program

#Id: 9648

#Unit 4. Cell Communication and Cell Signaling

MEK is a dual-specificity protein kinase

phosphorylates its target proteins on both tyrosine and serine/threonine

TLS Online TPP Program

#Id: 9649

#Unit 4. Cell Communication and Cell Signaling

In humans, there are three RAS, three Raf, two MEK, and two MAP proteins.