The intrinsic GTPase activity of the Gα subunit terminates G-protein signaling. Which of the following proteins accelerates this GTPase activity?

• A G-protein coupled receptor kinase (GRK)
• B Regulator of G-protein signaling (RGS) ✓
• C β-arrestin
• D Protein kinase A

Explanation

RGS proteins act as GTPase-activating proteins (GAPs) for Gα subunits, accelerating the hydrolysis of GTP to GDP and thereby terminating G-protein signaling. GRK phosphorylates activated GPCRs to promote β-arrestin binding and desensitization. β-arrestin uncouples the receptor from G-proteins. Protein kinase A is a downstream effector, not a direct regulator of Gα GTPase activity.

Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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