The glucagon receptor (GCGR) is one of the 15 members of the secretin-like (class B) family of G-protein-coupled receptors (GPCRs) in humans. Glucagon is a highly conserved 29 amino acid protein processed from proglucagon by PC2 in pancreatic α-cells. The principal actions of glucagon involve regulation of metabolic pathways involved in glucose homeostasis1. Glucagon binding to the GCGR activates adenylyl cyclase through heterotrimeric Gs G proteins, leading to an increase in intracellular cAMP levels and subsequent activation of PKA signaling.nThe glucagon receptor is a 485-amino acid protein with a central core consisting of seven membrane-spanning domains, an extracellular N-terminus and a cytoplasmic C-terminal tail.Glucagon receptors are widely expressed in multiple tissues including the liver, brain, pancreas, heart, kidney, and smooth muscle cell in the gastrointestinal tract and peripheral vasculature.Abnormal glucagon signaling is associated with hyperglycemia in patients with type 2 diabetes. Mice with homozygous null mutation of GCGR exhibit chronic hypoglycemia, extreme hyperglucagonemia, and α cell hyperplasia4. GCGR is a potential drug target for type 2 diabetes.