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, allowing cells to respond to various stimuli, such as hormones, neurotransmitters, and environmental changes. When a molecule binds to a GPCR, it activates an internal signaling pathway through the associated G-proteins. These receptors are involved in many physiological processes, including vision, taste, and smell, as well as regulating mood and immune responses. Due to their significant role in cell communication, GPCRs are important targets for many pharmaceuticals, making them a key focus in drug development.