A mutation in the alpha subunit of a G protein prevents GTP binding. What is the likely consequence of this mutation?

• A. The G protein remains inactive, unable to activate effector enzymes.
• B. The G protein dissociates into its subunits without GTP binding.
• C. The G protein can bind ATP instead of GTP.
• D. The G protein becomes permanently active, continuously activating effector enzymes.

Answer: (A)