GPCRs are proteins that span the cell membrane seven times and are involved in transmitting signals from outside the cell to the inside. When a ligand, such as a hormone or neurotransmitter, binds to a GPCR, it causes a conformational change in the receptor. This change activates a G protein, which then influences various intracellular pathways. The wide diversity of ligands that interact with GPCRs includes small molecules, ions, peptides, and large proteins.
