Question

GPCR activation leads to

• A. \( \text{DNA replication} \)
• B. \( \text{G-protein activation} \)
• C. \( \text{Ribosome formation} \)
• D. \( \text{ATP synthesis} \)

Hint:

Over 40% of all modern medicinal drugs target GPCRs because of their central role in human physiology.

Answer 1

The Correct Option is B

Concept: G-Protein Coupled Receptors (GPCRs) are the largest and most diverse group of membrane receptors in eukaryotes.
• They play a fundamental role in transmitting signals from outside the cell to the interior.
• These receptors interact with specialized proteins called G-proteins.

Step 1: The Mechanism of Activation.
GPCRs are transmembrane proteins that cross the lipid bilayer seven times. When a ligand (like a hormone or neurotransmitter) binds to the extracellular part of the receptor, the receptor undergoes a conformational change.

Step 2: Downstream Signaling.
This change allows the internal part of the receptor to act as a Guanine nucleotide Exchange Factor (GEF). It triggers the associated G-protein to swap its bound GDP for GTP, thereby "activating" the G-protein. The activated G-protein then dissociates and triggers further intracellular messengers. Final Answer: Activation of GPCRs directly leads to G-protein activation.