This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
True about G protein receptor is 
Select and explain. 
A. Intracellular and signal to heterotrimeric protein, B. Intracellular and signal to small protein, C. Cell membrane and signal to heterotrimeric protein, D. Cell membrane and signal to small protein
D: Cell membrane and signal to small protein
Answer: D: Cell membrane and signal to small protein 
Explanation: G protein receptor also called seven transmembrane receptor is locatelsmd in cell membrane and open stimulations transmits signal to G protein Ref:Guyton and Hall textbook of medical physiology 12th edition,page number:534,535,536