What basic function do the subunits in G proteins provide?

The subunits in G proteins play a crucial role in mediating signal transduction, which is the process by which cells respond to external signals and stimuli. G proteins are molecular switches that are activated by G protein-coupled receptors (GPCRs) on the cell membrane. When a ligand binds to the GPCR, it triggers a conformational change that activates the G protein, leading to the exchange of GDP for GTP on the alpha subunit. This activation causes the G protein to dissociate into its subunits (alpha, beta, and gamma), which can then interact with other proteins inside the cell, such as enzymes or ion channels. Through these interactions, G proteins help propagate the signal and initiate various cellular responses, such as changes in gene expression, enzyme activity, or cellular metabolism. This is fundamental for processes such as sensation, growth, and immune responses, highlighting their essential role in cellular communication and signaling pathways.