Which of the following pathways correctly shows how glycogen synthase is activated in response to the activation of IRS-1 by insulin binding? A)IRS-1 causes activation of protein kinase B which phosphorylates glycogen synthase kinase thus preventing phosphorylation of glycogen synthase B)IRS-1 activates a cascade that ultimately phosphorylates ERK which then binds to glycogen synthase C)IRS-1 activates phosphoinositide 3-kinase and the resulting PIP₃ is an allosteric activator of glycogen synthase D)IRS-1 activates guanylate cyclase and the resulting cGMP binds to glycogen synthase kinase thus preventing phosphorylation of glycogen synthase E)none of the above

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Quizplus · Accepted Answer

IRS-1 activates protein kinase B (also known as Akt) which then phosphorylates glycogen synthase kinase, thereby preventing its ability to phosphorylate glycogen synthase. This allows for the activation of glycogen synthase and glycogen synthesis in response to insulin binding. B, C, and D are incorrect as they do not accurately describe the pathway for activation of glycogen synthase by insulin.

Which of the Following Pathways Correctly Shows How Glycogen Synthase