Fig. 1: Phylogenetic analysis and functional tests of GCGR in vertebrates.
From: Constitutively active glucagon receptor drives high blood glucose in birds
a, Activation of CRE-luciferase activity (green, no constitutive activity; pink, weak constitutive activity; red, strong constitutive activity) by GCGR homologues from various species (top) at similar protein expression levels (middle). GCGR has constitutive activity in non-placental vertebrates. Bottom, approximate blood glucose concentration. b, Constitutive activities of GCGRs (green, placental mammals; blue, non-placental mammals; red, birds). A higher slope indicates a higher level of Gs constitutive activity. CcGCGR, Cuculus canorus GCGR; CfGCGR, Camelus ferus GCGR; ClGCGR, Chiroxiphia lanceolata GCGR; MdGCGR, Monodelphis domestica GCGR; NcGCGR, Neopelma chrysocephalum GCGR; TaGCGR, Tachyglossus aculeatus GCGR. c, Concentration-response curves of GCG stimulation of GCGRs in HEK293. d, Blood glucose, glycogen and GCGR mRNA expression (normalized to β-actin gene expression) in the liver of different species. n = 3 per group (green, mammals; red, birds; yellow, reptiles; purple, amphibians; blue, fish).
