An SH2-containing protein contains a mutation that changes its binding pocket such that tyrosine and phosphotyrosine bind with equal affinity.As a result,MEK activity:
A)decreases due to changes in Raf activation.
B)decreases due to allosteric inhibition of SH2-domain binding.
C)increases with ligand binding-induced dimerization.
D)does not change with receptor dimerization and transautophosphorylation.

Question

Quizplus · Accepted Answer

The mutation in the SH2-containing protein alters the binding pocket such that both tyrosine and phosphotyrosine bind with equal affinity. However, this does not necessarily mean that MEK activity is affected. MEK is downstream of the receptor activation and is activated by phosphorylation by Raf. The mutation in the SH2-containing protein only affects receptor dimerization and transautophosphorylation, which leads to downstream signaling. Therefore, MEK activity does not change as a result of this mutation. Option D correctly states this fact.

An SH2-Containing Protein Contains a Mutation That Changes Its Binding