G protein-coupled receptor

G protein-coupled receptors (GPCRs) are specialized proteins located on cell surfaces that detect signals like hormones, neurotransmitters, and environmental stimuli. When a signaling molecule binds to a GPCR, it triggers a change in the receptor's shape, activating internal proteins called G proteins. These G proteins then set off a cascade of events inside the cell, leading to a response such as altering gene activity, releasing chemicals, or changing cell behavior. GPCRs are essential for many processes, including sensory perception, immune response, and regulation of mood and blood pressure.