Steroid hormones differ from peptide hormones in their mechanism of action because steroids:
- A Bind intracellular nuclear receptors that act as transcription factors ✓
- B Act on cell-surface G-protein coupled receptors
- C Use cAMP as their exclusive second messenger
- D Require receptor tyrosine kinase for signal transduction
Correct answer: A. Bind intracellular nuclear receptors that act as transcription factors
Explanation
Steroids are lipophilic and cross the plasma membrane to bind cytoplasmic or nuclear receptors; the hormone-receptor complex dimerises, translocates to the nucleus, and binds hormone response elements (HREs) to regulate gene transcription. GPCRs and cAMP are used by catecholamines and peptide hormones. Receptor tyrosine kinases are used by insulin and growth factors, not steroids.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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