Carbohydrate metabolism: insulin signalling to GLUT4: practice question

A Biochemistry question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Biochemistry · Carbohydrate metabolism: insulin signalling to GLUT4

Sample item

After insulin binds its receptor, which downstream sequence mainly leads to GLUT4 translocation to the plasma membrane in muscle and adipocytes?

AGs protein, adenylyl cyclase and protein kinase ABIRS-1 phosphorylation, PI3 kinase and Akt (protein kinase B)CJAK2 and STAT5 phosphorylationDGq protein, phospholipase C and protein kinase C

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. IRS-1 phosphorylation, PI3 kinase and Akt (protein kinase B)

The insulin receptor is a tyrosine kinase that phosphorylates IRS proteins. IRS-1 activates PI3 kinase, which generates PIP3 and activates Akt, and this promotes fusion of GLUT4 vesicles with the plasma membrane. The Ras-MAP kinase branch mainly mediates growth and mitogenic effects.

Option by option

A. Gs protein, adenylyl cyclase and protein kinase A
Gs-cAMP-PKA signalling is the pathway used by glucagon and adrenaline, not insulin.
B. IRS-1 phosphorylation, PI3 kinase and Akt (protein kinase B) (correct)
Correct. The IRS-1, PI3 kinase and Akt pathway drives GLUT4 vesicle translocation.
C. JAK2 and STAT5 phosphorylation
JAK-STAT signalling is used by cytokine and growth hormone receptors, not the insulin receptor.
D. Gq protein, phospholipase C and protein kinase C
Gq-phospholipase C-PKC is used by receptors such as alpha-1 adrenergic receptors.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is B, IRS-1 phosphorylation, PI3 kinase and Akt (protein kinase B). The insulin receptor is a tyrosine kinase that phosphorylates IRS proteins.

Why is "Gs protein, adenylyl cyclase and protein kinase A" not the answer?

Gs-cAMP-PKA signalling is the pathway used by glucagon and adrenaline, not insulin.

Why is "JAK2 and STAT5 phosphorylation" not the answer?

JAK-STAT signalling is used by cytokine and growth hormone receptors, not the insulin receptor.

Why is "Gq protein, phospholipase C and protein kinase C" not the answer?

Gq-phospholipase C-PKC is used by receptors such as alpha-1 adrenergic receptors.

What concept does this question test?

It tests Carbohydrate metabolism: insulin signalling to GLUT4 in Biochemistry. IRS-1 activates PI3 kinase, which generates PIP3 and activates Akt, and this promotes fusion of GLUT4 vesicles with the plasma membrane. The Ras-MAP kinase branch mainly mediates growth and mitogenic effects.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Carbohydrate metabolism: insulin signalling to GLUT4?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.