Which of the following is true for a G-protein?
A. When an agonist binds to the binding site of a G-protein-coupled receptor (GPCR), this leads to GDP displacing a GTP bound to the alpha subunit of the G-protein.
B. When an antagonist binds to the binding site of a G-protein-coupled receptor (GPCR), this has no effect on the GDP that is 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.