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 growth factor binds a surface receptor; the receptor dimerises and autophosphorylates, recruits Grb2 and SOS, and switches on the Ras-MAPK cascade. Which receptor class initiates this pathway?

AG protein-coupled receptorBReceptor guanylyl cyclaseCNuclear hormone receptorDReceptor tyrosine kinase

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

The answer and the reasoning

D. Receptor tyrosine kinase

Phosphorylated residues on the receptor create docking sites for adaptor proteins, which activate Ras by promoting GTP exchange. Ras then starts the MAP kinase cascade that stimulates proliferation. Mutations that activate this class or Ras are common in cancer.

Option by option

A. G protein-coupled receptor
G protein-coupled receptors use heterotrimeric G proteins and second messengers, not Grb2.
B. Receptor guanylyl cyclase
Receptor guanylyl cyclases produce cGMP and do not recruit Grb2 and SOS.
C. Nuclear hormone receptor
Nuclear hormone receptors act as transcription factors and are not cell-surface receptors.
D. Receptor tyrosine kinase (correct)
Correct. Autophosphorylation creates docking sites for Grb2 and SOS, which activate Ras.

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 D, Receptor tyrosine kinase. Phosphorylated residues on the receptor create docking sites for adaptor proteins, which activate Ras by promoting GTP exchange.

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

G protein-coupled receptors use heterotrimeric G proteins and second messengers, not Grb2.

Why is "Receptor guanylyl cyclase" not the answer?

Receptor guanylyl cyclases produce cGMP and do not recruit Grb2 and SOS.

Why is "Nuclear hormone receptor" not the answer?

Nuclear hormone receptors act as transcription factors and are not cell-surface receptors.

What concept does this question test?

It tests Insulin signalling: receptor tyrosine kinase in Biochemistry. Ras then starts the MAP kinase cascade that stimulates proliferation. Mutations that activate this class or Ras are common in cancer.

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 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.