The glucagon receptor (GCGR) is a class B G protein-coupled receptor for glucagon, the 29-amino-acid hormone released from pancreatic alpha-cells. It is expressed most densely on hepatocytes, with lower expression in kidney, adipose tissue, heart and brain. Glucagon and GLP-1 both derive from proglucagon, which is why sequence homology makes cross-reactive multi-receptor peptides chemically feasible.
Reported signalling
GCGR activation couples through Gs to adenylate cyclase and cAMP, driving hepatic glycogenolysis and gluconeogenesis — the classic counter-regulatory response to falling blood glucose. Beyond glucose output, published work describes increased hepatic fatty-acid oxidation, raised energy expenditure and reduced hepatic lipid content in rodent models, which is the rationale for including a glucagon arm in metabolic research peptides rather than avoiding it.
Why it matters
Adding GCGR agonism to incretin activity is the design idea behind dual and triple agonists. Survodutide and mazdutide engage GCGR alongside GLP-1; retatrutide adds GIP as well. The trade-off studied in the literature is that unopposed glucagon action raises glucose, so the incretin arm has to be balanced against it — receptor potency ratios, not just receptor count, define these molecules.
Related terms
GIP · incretin. See the glucagon research family, Survodutide, Retatrutide, and Survodutide vs Mazdutide.