Final answer:
G-protein coupled receptors have seven transmembrane domains and share the common feature of activating G-proteins when bound by a ligand. This activation leads to interactions with ion channels or enzymes in the membrane, resulting in cellular responses. Each receptor has its own specific domain and binding site, allowing it to bind to different ligands and activate different cellular processes.
Step-by-step explanation:
G-protein coupled receptors are a diverse family of receptors that share a common feature. They all have seven transmembrane domains, which allow them to span the cell membrane. When a signalling molecule (ligand) binds to the G-protein coupled receptor, it activates a membrane protein called a G-protein. The G-protein then interacts with either an ion channel or an enzyme in the membrane, which leads to a cellular response. Each G-protein coupled receptor has its own specific extracellular domain and G-protein-binding site, which allows it to bind to different ligands and activate different cellular processes.