Insulin signalling: receptor tyrosine kinase: 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 · Insulin signalling: receptor tyrosine kinase

Sample item

A gastrointestinal stromal tumour carries a gain-of-function mutation in the KIT surface receptor, which dimerises and signals without ligand. Imatinib controls the tumour by blocking the intrinsic catalytic domain of which receptor class?

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

The answer and the reasoning

D. Receptor tyrosine kinase

KIT belongs to the receptor family whose intracellular domain phosphorylates tyrosine residues, as do PDGFR and the insulin receptor. Constitutive activation drives proliferation and is blocked by imatinib at the ATP-binding site. This is a targeted therapy aimed at the mutated driver.

Option by option

  • A. Receptor guanylyl cyclase

    Receptor guanylyl cyclases are not involved in this tumour.

  • B. G protein-coupled receptor

    G protein-coupled receptors are not the target of imatinib in this tumour.

  • C. Cytokine receptor with JAK

    Cytokine receptors depend on separate JAK enzymes and KIT does not belong to this group.

  • D. Receptor tyrosine kinase (correct)

    Correct. KIT is a receptor with intrinsic catalytic activity, and imatinib blocks its ATP-binding site.

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.

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Questions about this Biochemistry question

What is the answer to this Biochemistry question?

The best answer is D, Receptor tyrosine kinase. KIT belongs to the receptor family whose intracellular domain phosphorylates tyrosine residues, as do PDGFR and the insulin receptor.

Why is "Receptor guanylyl cyclase" not the answer?

Receptor guanylyl cyclases are not involved in this tumour.

Why is "G protein-coupled receptor" not the answer?

G protein-coupled receptors are not the target of imatinib in this tumour.

Why is "Cytokine receptor with JAK" not the answer?

Cytokine receptors depend on separate JAK enzymes and KIT does not belong to this group.

What concept does this question test?

It tests Insulin signalling: receptor tyrosine kinase in Biochemistry. Constitutive activation drives proliferation and is blocked by imatinib at the ATP-binding site. This is a targeted therapy aimed at the mutated driver.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Insulin signalling: receptor tyrosine kinase?

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.