Glucagon receptor (GCGR), a G protein-coupled receptor predominantly expressed in the liver and, to a lesser extent, in other tissues such as the pancreas, kidney, and brain. The natural ligand for this receptor is glucagon, a hormone secreted by pancreatic alpha cells that plays a critical counter-regulatory role to insulin. Glucagon binding to GCGR stimulates hepatic glycogenolysis and gluconeogenesis, thereby increasing blood glucose levels. Crotedumab functions as a competitive antagonist by binding with high affinity to the extracellular domain of the glucagon receptor.