RAR-related orphan receptor
Encyclopedia
The RAR-related orphan receptors (RORs) are members of the nuclear receptor
family of intracellular
transcription factor
s. There are three forms of ROR, ROR-α
, -β
, and -γ
and each is encoded by a separate gene . The RORs are somewhat unusual in that they appear to bind as monomers to hormone response element
s as opposed to the majority of other nuclear receptors which bind as dimers.
has been reported to be the endogenous ligand
for ROR-α while CGP 52608
has been identified as a ROR-α selective synthetic ligand. However X-ray crystallographic ( and ) and functional data both suggest that cholesterol or a cholesterol derivative may be the endogenous ligand.
In contrast, all-trans retinoic acid binds with high affinity to ROR-β and -γ but not ROR-α.
Nuclear receptor
In the field of molecular biology, nuclear receptors are a class of proteins found within cells that are responsible for sensing steroid and thyroid hormones and certain other molecules...
family 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...
transcription factor
Transcription factor
In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...
s. There are three forms of ROR, ROR-α
RAR-related orphan receptor alpha
RAR-related orphan receptor alpha , also known as NR1F1 is a nuclear receptor that in humans is encoded by the RORA gene.- Function :...
, -β
RAR-related orphan receptor beta
RAR-related orphan receptor beta , also known as NR1F2 is a nuclear receptor that in humans is encoded by the RORB gene.- Function :...
, and -γ
RAR-related orphan receptor gamma
RAR-related orphan receptor gamma is a protein that in humans is encoded by the RORC gene. RORγ is member of the nuclear receptor family of transcription factors.- Gene expression :...
and each is encoded by a separate gene . The RORs are somewhat unusual in that they appear to bind as monomers to hormone response element
Hormone response element
A hormone response element is a response element for hormones, a short sequence of DNA within the promoter of a gene that is able to bind a specific hormone receptor complex and therefore regulate transcription...
s as opposed to the majority of other nuclear receptors which bind as dimers.
Ligands
MelatoninMelatonin
Melatonin , also known chemically as N-acetyl-5-methoxytryptamine, is a naturally occurring compound found in animals, plants, and microbes...
has been reported to be the endogenous ligand
Ligand (biochemistry)
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. In a narrower sense, it is a signal triggering molecule, binding to a site on a target protein.The binding occurs by intermolecular forces, such as ionic bonds, hydrogen...
for ROR-α while CGP 52608
CGP 52608
CGP 52608 is a selective ligand of the RAR-related orphan receptor alpha. CGP 52608 has also been reported to possess antiarthritic activity....
has been identified as a ROR-α selective synthetic ligand. However X-ray crystallographic ( and ) and functional data both suggest that cholesterol or a cholesterol derivative may be the endogenous ligand.
In contrast, all-trans retinoic acid binds with high affinity to ROR-β and -γ but not ROR-α.
Function
The three forms of RORs fulfill a number of critical roles including:- ROR-α - development of the cerebellumCerebellumThe cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
and lymph nodeLymph nodeA lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...
s, lipid metabolismLipid metabolismLipid metabolism refers to the processes that involve the intercourse and degradation of lipids.The types of lipids involved include:* Bile salts* Cholesterols* Eicosanoids* Glycolipids* Ketone bodies* Fatty acids - see also fatty acid metabolism...
, immune response, maintenance of boneBoneBones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue... - ROR-β - precise role unknown but highly expressed in the brain and retina
- ROR-γ - lymph node development and immune response, survival of T helper 17 cellT helper 17 cellT helper 17 cells are a subset of T helper cells producing interleukin 17 discovered in 2007. They are considered developmentally distinct from Th1 and Th2 cells and excessive amounts of the cell are thought to play a key role in autoimmune disease such as multiple sclerosis , but also...
s