How is the G protein cellular response inactivated?

The G protein cellular response is inactivated primarily by the exchange of GTP for GDP. When a G protein is activated, it binds to GTP, and this activation initiates a signaling cascade within the cell. However, for the signaling to return to its resting state, the G protein must deactivate. This occurs when the GTP bound to the G protein is hydrolyzed to GDP. This hydrolysis process causes a conformational change in the G protein, effectively inactivating it and allowing it to dissociate from its effector. Consequently, to ensure that the signaling pathway does not remain active indefinitely, this recycling of GDP and GTP is crucial in the regulation of the pathway.

In contrast, degrading the receptor, blocking its interaction with the effector, or synthesizing new proteins would not directly terminate the G protein activity itself but rather affect the context in which G proteins operate or alter other cellular functions. The most direct mechanism for inactivating G protein signaling is indeed the conversion of GTP back to GDP.