G protein-coupled receptors (GPCRs) are located in the cell membrane of eukaryotic organisms including animals, plants, yeast and choanoflagellates. Each GPCR is made up of a single polypeptide that’s folded into a globular shape. It lies embedded in the plasma membrane of the cell. 7 segments of a GPCR molecule cover the entire width of the membrane with the intervening portions looping inside and outside the cell.