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MBBS QUESTION #10302
Question 1
A hormone that binds a cell-surface G-protein-coupled receptor, activating adenylate cyclase and raising intracellular cAMP to trigger downstream effects, is an example of which broad category of cell signaling?
  • Direct nuclear receptor signaling, requiring a lipid-soluble hormone
  • Second-messenger signaling via a G-protein coupled receptor✔️
  • Ligand-gated ion channel signaling exclusively
  • Receptor tyrosine kinase autophosphorylation only
Correct Answer Explanation
G-protein coupled receptors transduce an extracellular signal (hormone binding) into an intracellular second messenger response (here, cAMP via adenylate cyclase), amplifying the signal and triggering downstream kinase cascades — a mechanism used by many water-soluble hormones (e.g., glucagon, ADH at V2 receptors) that cannot cross the plasma membrane.