This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
Action of alpha subunit of G-protein is: 
Select and explain. 
A. Binding of agonist, B. Conversion of GDP to GTP, C. Breakdown of GTP to GDP, D. Internalization of receptors
C: Breakdown of GTP to GDP
Answer: C: Breakdown of GTP to GDP 
Explanation: Ans. (C) Breakdown of GTP to GDP(Ref: KDT 8th/e p54)Alpha subunit of G protein contains GTPase activity and thus dissociates GTP to form GDP. This result in re-uniting a subunit with b and g subunit