Which of the following is true for a G-protein?

A. After the ATP-ase of the alpha subunit of a G protein converts the ATP bound to the alpha subunit to ADP and inorganic phosphate (Pi ), the alpha subunit of the G-protein recombines with the beta and gamma subunits of the G-protein.

 B. When an antagonist binds to the binding site of a G-protein-coupled receptor (GPCR), this leads to GTP displacing a GDP bound to the alpha subunit of the G-protein.

C. When GDP binds to an alpha subunit of the G-protein, this leads to the alpha subunit of the G-protein dissociating from the beta and gamma subunits of the G-protein.