Although the major metabolic effect of insulin is to promote fuel storage following meals, this hormone also has growth factor activity. One of the growth-promoting responses to insulin action is an increase in the rate of translation. Which of the following proteins of translation is a target of insulin-mediated action, the consequence of which is a reduced level of phosphorylation and thus increased activity?
A) 4EBP
B) eEF-2
C) eIF-2
D) eIF-2B
E) eRF

Question

Quizplus · Accepted Answer

With respect to insulin effects on translation, these signaling cascades ultimately affect the activity of 2 kinases, mTOR and glycogen synthase kinase 3b (GSK3β). GSK3β normally phosphorylates the translation initiation factor eIF-2B, which is responsible for the exchange of GDP for GTP bound to eIF-2. This nucleotide exchange reaction is essential to reactivate eIF-2 during each round of translation. When phosphorylated eIF-2B is much slower at catalyzing the exchange, the effect of insulin in this cascade is to activate the kinase PKB/Akt which in turn phosphorylates GSK3b. When GSK3b is phosphorylated it can no longer phosphorylate eIF-2B, thus in response to insulin the nucleotide exchange action of eIF-2B is high leading to increased translation.

Although the Major Metabolic Effect of Insulin Is to Promote