The glucagon receptor is a 62 kDa

KDA

KDA may refer to:* Karachi Development Authority* Kongsberg Defence & Aerospace* Kotelawala Defence Academy* Kramer Design Associates* Lithium diisopropylamide, KDA is the potassium analogue of lithium diisopropylamideOr kDa may refer to:...

 protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that is activated by glucagon

Glucagon

Glucagon, a hormone secreted by the pancreas, raises blood glucose levels. Its effect is opposite that of insulin, which lowers blood glucose levels. The pancreas releases glucagon when blood sugar levels fall too low. Glucagon causes the liver to convert stored glycogen into glucose, which is...

 and is a member of the class B G-protein coupled family of receptors, coupled to G alpha i, G_s

Gs alpha subunit

The Gs alpha subunit is a heterotrimeric G protein subunit that activates the cAMP-dependent pathway by activating adenylate cyclase.-Receptors:The G protein-coupled receptors that couple to this kind of G-protein include:...

 and to a lesser extent G alpha q. Stimulation of the receptor results in activation of adenylate cyclase

Adenylate cyclase

Adenylate cyclase is part of the G protein signalling cascade, which transmits chemical signals from outside the cell across the membrane to the inside of the cell ....

 and increased levels of intracellular

Intracellular

Not to be confused with intercellular, meaning "between cells".In cell biology, molecular biology and related fields, the word intracellular means "inside the cell".It is used in contrast to extracellular...

 cAMP

Cyclic adenosine monophosphate

Cyclic adenosine monophosphate is a second messenger important in many biological processes...

. In humans, the glucagon receptor is encoded by the GCGR gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

Glucagon receptors are mainly expressed in liver

Liver

The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

 and in kidney

Kidney

The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...

 with lesser amounts found in heart

Heart

The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

, adipose tissue, spleen

Spleen

The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...

, thymus

Thymus

The thymus is a specialized organ of the immune system. The thymus produces and "educates" T-lymphocytes , which are critical cells of the adaptive immune system....

, adrenal glands, pancreas

Pancreas

The pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as a digestive organ, secreting pancreatic juice containing digestive enzymes that assist...

, cerebral cortex

Cerebral cortex

The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...

, and gastrointestinal tract

Gastrointestinal tract

The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....

.

Clinical significance

A missense mutation

Missense mutation

In genetics, a missense mutation is a point mutation in which a single nucleotide is changed, resulting in a codon that codes for a different amino acid . This can render the resulting protein nonfunctional...

 in the GCGR gene is associated with diabetes mellitus type 2

Diabetes mellitus type 2

Diabetes mellitus type 2formerly non-insulin-dependent diabetes mellitus or adult-onset diabetesis a metabolic disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Diabetes is often initially managed by increasing exercise and...

.

Inactivating mutation

Mutation

In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...

 of glucagon receptor in humans causes resistance to glucagon

Glucagon

Glucagon, a hormone secreted by the pancreas, raises blood glucose levels. Its effect is opposite that of insulin, which lowers blood glucose levels. The pancreas releases glucagon when blood sugar levels fall too low. Glucagon causes the liver to convert stored glycogen into glucose, which is...

 and is associated with pancreatic alpha cell hyperplasia

Hyperplasia

Hyperplasia means increase in number of cells/proliferation of cells. It may result in the gross enlargement of an organ and the term is sometimes mixed with benign neoplasia/ benign tumor....

, nesidioblastosis

Nesidioblastosis

Nesidioblastosis is beta cell hyperplasia, consisting of the proliferation of islet cells from pancreatic ducts. It is a cause of hypoglycemia and hyperinsulinemia in a number of infants and newborns. Recently, this condition has been recognized in adolescents and adults and occurs in 5% of...

, hyperglucagonemia, and pancreatic neuroendocrine tumors

Neuroendocrine tumors

Neuroendocrine tumors are neoplasms that arise from cells of the endocrine and nervous systems. Many are benign, while some are cancers...

.

Further reading