What do the beta and gamma subunits of G proteins primarily do?

The beta and gamma subunits of G proteins play a crucial role in the regulation and stabilization of the alpha subunit. Their primary function is to anchor the alpha subunit in the cell membrane, ensuring that it remains in the correct position to interact with associated receptors and effectors. This anchoring is essential for maintaining the overall functional integrity of the G protein complex while also facilitating the proper signaling pathways that are initiated by various ligands.

While the other choices mention important processes related to G proteins and their functions, they do not accurately represent the primary role of the beta and gamma subunits. For instance, ion channels can indeed be regulated by G proteins, but this is primarily due to the action of the alpha subunit rather than the beta and gamma subunits specifically. Similarly, GTP breakdown is a function associated with the alpha subunit, which interacts with GTP and carries out the hydrolysis process. The activation of second messengers often involves signaling cascades that are initiated by the alpha subunit as well, rather than the beta and gamma subunits themselves driving that activation.