This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
True about G protein coupled receptors is? 
Select and explain. 
A. G proteins bind to hormones on the cell surface, B. All the three subunits alpha, beta and gamma should bind each other for G protein to act, C. G proteins act as inhibitory and excitatory because of difference in alpha subunit, D. G protein is bound to GTP in resting state
C: G proteins act as inhibitory and excitatory because of difference in alpha subunit
Answer: C: G proteins act as inhibitory and excitatory because of difference in alpha subunit 
Explanation: None