Final answer:
G proteins are activated by a ligand-receptor interaction that prompts the exchange of GDP for GTP. The activated G protein then moves to and activates an effector protein, initiating intracellular signaling pathways and leading to a cellular response.
Step-by-step explanation:
Guanosine triphosphate (GTP) hydrolases, also known as GTPases, are a family of enzymes involved in the transmission of cellular signals. The GTPase involved in your question appears to be the G protein, which is activated during the signaling process from a cell-surface receptor to various effector proteins inside the cell.
When a signaling molecule (ligand) binds to its receptor on the cell membrane, the receptor undergoes a conformational change. This change is detected by the G protein, which is then activated when it exchanges a bound guanosine diphosphate (GDP) for guanosine triphosphate (GTP).
Once activated by GTP binding, the G protein physically moves from the receptor to the effector protein to activate the latter. The primary function of the activated G protein is to relay the signal from the extracellular ligand-receptor interaction to intracellular signaling pathways, resulting in a cellular response.