G Protein Coupled Receptors (GPCRs) are a large family of proteins found in the cell membrane. They play a crucial role in transmitting signals from outside the cell to the inside, helping cells respond to various stimuli like hormones, neurotransmitters, and environmental changes. When a molecule binds to a GPCR, it activates a G protein, which then triggers a series of cellular responses. These receptors are involved in many physiological processes, including vision, taste, and immune responses. Due to their significant role in cell signaling, GPCRs are important targets for drug development, with many medications designed to interact with them to treat various conditions.