The Following Happens When a G-Protein-Coupled Receptor Activates a G

Question

The following happens when a G-protein-coupled receptor activates a G protein.
A)The β subunit exchanges its bound GDP for GTP.
B)The GDP bound to the α subunit is phosphorylated to form bound GTP.
C)The α subunit exchanges its bound GDP for GTP.
D)It activates the α subunit and inactivates the βγ complex.

Accepted Answer

When a G-protein-coupled receptor activates a G protein, the α subunit exchanges its bound GDP for GTP. This activates the α subunit, allowing it to interact with downstream effector proteins, while the βγ complex remains associated and may also interact with effectors. The exchange of GDP for GTP on the α subunit is facilitated by the binding of the receptor to the G protein, causing a conformational change that promotes GDP release and GTP binding.