 G protein-coupled receptor

G protein-coupled receptors (GPCRs) are a large family of membrane proteins that play a critical role in cellular signaling. These receptors are characterized by their ability to pass through the cell membrane seven times (hence they are also known as seven-transmembrane receptors). GPCRs respond to a variety of external signals, including hormones, neurotransmitters, and environmental stimuli, and are involved in many physiological processes.