GCGR
Description
The GCGR (glucagon receptor) is a protein-coding gene located on chromosome 17.
The glucagon receptor is a 62 kDa protein that is activated by glucagon and is a member of the class B G-protein coupled family of receptors, coupled to G alpha i, Gs and to a lesser extent G alpha q. Stimulation of the receptor results in the activation of adenylate cyclase and phospholipase C and in increased levels of the secondary messengers intracellular cAMP and calcium. In humans, the glucagon receptor is encoded by the GCGR gene. Glucagon receptors are mainly expressed in liver and in kidney with lesser amounts found in heart, adipose tissue, spleen, thymus, adrenal glands, pancreas, cerebral cortex, and gastrointestinal tract.
== Signal transduction pathway == A glucagon receptor, upon binding with the signaling molecule glucagon, initiates a signal transduction pathway that begins with the activation of adenylate cyclase, which in turn produces cyclic AMP (cAMP). Protein kinase A, whose activation is dependent on the increased levels of cAMP, is responsible for the ensuing cellular response in the form of protein kinase 1 and 2. The ligand-bound glucagon receptor can also initiate a concurrent signaling pathway that is independent of cAMP by activating phospholipase C. Phospholipase C produces DAG and IP3 from PIP2, a phospholipid phospholipase C cleaves off of the plasma membrane. Ca2+ stores inside the cell release Ca2+ when its calcium channels are bound by IP3.
== Structure ==
The 3D crystallographic structures of the seven transmembrane helical domain (7TM) and the extracellular domain (ECD) and an electron microscopy (EM) map of full length glucagon receptor have been determined. Furthermore, the structural dynamics of an active state complex of the Glucagon receptor, Glucagon, the Receptor activity-modifying protein, and the G-protein C-terminus has been determined using a computational and experimental approach.
G-protein coupled receptor for glucagon that plays a central role in the regulation of blood glucose levels and glucose homeostasis. Regulates the rate of hepatic glucose production by promoting glycogen hydrolysis and gluconeogenesis. Plays an important role in mediating the responses to fasting. Ligand binding causes a conformation change that triggers signaling via guanine nucleotide-binding proteins (G proteins) and modulates the activity of down-stream effectors, such as adenylate cyclase. Promotes activation of adenylate cyclase. Besides, plays a role in signaling via a phosphatidylinositol-calcium second messenger system.
GCGR is also known as GGR, GL-R, MVAH.
