G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors involved in signal transduction. They share a common structure and signal through heterotrimeric G-Proteins. GPCR-Autoantibodies are functional autoantibodies that bind to GPCR and activate second-messenger cascades in an uncontrolled manner. (Description adapted from: https://www.ncbi.nlm.nih.gov/mesh/68043562)