Final answer:
G-protein-linked receptors bind to ligands to initiate cellular responses through activation of associated G-proteins.
Step-by-step explanation:
G-protein-linked receptors bind to various ligands, which are molecules that can bind to the receptors and activate them. Some examples of ligands that can bind to G-protein-linked receptors include neurotransmitters like dopamine and serotonin, hormones like adrenaline and insulin, and various chemicals and drugs.
Once the ligand binds to the receptor, it causes a shape change in the receptor, which then activates an associated G-protein. The activated G-protein can then interact with other membrane proteins, such as ion channels or enzymes, to initiate specific cellular responses or signal transduction pathways.
Overall, the binding of ligands to G-protein-linked receptors plays a crucial role in cell signaling and communication, allowing cells to respond to different stimuli and maintain various physiological processes.