Guanylyl cyclase c
Encyclopedia
Guanylate cyclase 2C, also known as guanylyl cyclase C (GC-C), intestinal guanylate cyclase, guanylate cyclase-C receptor, or the heat-stable enterotoxin receptor (hSTAR) is an enzyme
that in humans is encoded by the GUCY2C gene
.
Guanylyl cyclase is an enzyme found in the luminal
aspect of intestinal
epithelium
and dopamine neurons in the brain . The receptor has an extracellular
ligand
-binding domain, a single transmembrane region, a region with sequence similar to that of protein kinase
s, and a C-terminal
guanylate cyclase
domain. Tyrosine kinase
activity mediates the GC-C signaling pathway within the cell
.
for heat-stable enterotoxin
s that are responsible for acute secretory diarrhea
. Heat-stable enterotoxins are produced by pathogens such as Escherichia coli
. Knockout
mice deficient in the GC-C gene do not show secretory diarrhea on infection with E. coli, though they do with cholera
toxin. This demonstrates the specificity of the GC-C receptor.
-specific for intestinal epithelium, it can be used for detection of metastatic disease.
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
that in humans is encoded by the GUCY2C 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...
.
Guanylyl cyclase is an enzyme found in the luminal
Lumen (anatomy)
A lumen in biology is the inside space of a tubular structure, such as an artery or intestine...
aspect of intestinal
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
epithelium
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
and dopamine neurons in the brain . The receptor has an extracellular
Extracellular
In cell biology, molecular biology and related fields, the word extracellular means "outside the cell". This space is usually taken to be outside the plasma membranes, and occupied by fluid...
ligand
Ligand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...
-binding domain, a single transmembrane region, a region with sequence similar to that of protein kinase
Protein kinase
A protein kinase is a kinase enzyme that modifies other proteins by chemically adding phosphate groups to them . Phosphorylation usually results in a functional change of the target protein by changing enzyme activity, cellular location, or association with other proteins...
s, and a C-terminal
C-terminal end
The C-terminus is the end of an amino acid chain , terminated by a free carboxyl group . When the protein is translated from messenger RNA, it is created from N-terminus to C-terminus...
guanylate cyclase
Guanylate cyclase
-Reaction:Guanylate cyclase catalyzes the reaction of guanosine triphosphate to 3',5'-cyclic guanosine monophosphate and pyrophosphate:-Types:...
domain. Tyrosine kinase
Tyrosine kinase
A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to a protein in a cell. It functions as an "on" or "off" switch in many cellular functions....
activity mediates the GC-C signaling pathway within the cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
.
Functions
GC-C is a key receptorReceptor (biochemistry)
In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...
for heat-stable enterotoxin
Enterotoxin
An enterotoxin is a protein toxin released by a microorganism in the intestine. Enterotoxins are chromosomally encoded exotoxins that are produced and secreted from several bacterial organisms. They are often heat-stable, and are of low molecular weight and water-soluble...
s that are responsible for acute secretory diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
. Heat-stable enterotoxins are produced by pathogens such as Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
. Knockout
Gene knockout
A gene knockout is a genetic technique in which one of an organism's genes is made inoperative . Also known as knockout organisms or simply knockouts, they are used in learning about a gene that has been sequenced, but which has an unknown or incompletely known function...
mice deficient in the GC-C gene do not show secretory diarrhea on infection with E. coli, though they do with cholera
Cholera
Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...
toxin. This demonstrates the specificity of the GC-C receptor.
Diagnostic application
Because GC-C is tissueTissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
-specific for intestinal epithelium, it can be used for detection of metastatic disease.