Endothelin receptor type B, also known as ET
B is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
that in humans is encoded by the ''EDNRB''
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
.
Function
Endothelin receptor type B is a
G protein-coupled receptor
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily-related p ...
which activates a phosphatidylinositol-calcium second messenger system. Its ligand,
endothelin
Endothelins are peptides with receptors and effects in many body organs. Endothelin constricts blood vessels and raises blood pressure. The endothelins are normally kept in balance by other mechanisms, but when overexpressed, they contribute ...
, consists of a family of three potent vasoactive peptides: ET
1, ET
2, and ET
3. A splice variant, named SVR, has been described; the sequence of the ETB-SVR receptor is identical to ETRB except for the intracellular C-terminal domain. While both splice variants bind ET
1, they exhibit different responses upon binding which suggests that they may be functionally distinct.
Regulation
In
melanocytic
Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea),
the inner ear,
vaginal epithelium, meninges,
bones,
and heart.
...
cells the EDNRB gene is regulated by the
microphthalmia-associated transcription factor. Mutations in either gene are links to
Waardenburg syndrome
Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes (or one blue eye and one brown eye), a white foreloc ...
.
Clinical significance
The multigenic disorder,
Hirschsprung disease
Hirschsprung's disease (HD or HSCR) is a birth defect in which nerves are missing from parts of the intestine. The most prominent symptom is constipation. Other symptoms may include vomiting, abdominal pain, diarrhea and slow growth. Symptoms ...
type 2, is due to mutation in endothelin receptor type B gene.
Animals
In
horse
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
s, a mutation in the middle of the EDNRB gene, Ile118Lys, when
homozygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism.
Mo ...
, causes
Lethal White Syndrome
Lethal white syndrome (LWS), also called overo lethal white syndrome (OLWS), lethal white overo (LWO), and overo lethal white foal syndrome (OLWFS), is an autosomal genetic disorder most prevalent in the American Paint Horse. Affected foals are bo ...
.
In this mutation, a mismatch in the
DNA replication causes
lysine to be made instead of
isoleucine.
[ The resulting EDNRB protein is unable to fulfill its role in the development of the embryo, limiting the migration of the melanocyte and enteric neuron precursors. A single copy of the EDNRB mutation, the ]heterozygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism.
Mo ...
state, produces an identifiable and completely benign spotted coat color called frame overo.
Interactions
Endothelin receptor type B has been shown to interact
Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization using innovative strategies to advocate for the legal and human rights of children with intersex traits. The organizati ...
with Caveolin 1
Caveolin-1 is a protein that in humans is encoded by the ''CAV1'' gene.
Function
The scaffolding protein encoded by this gene is the main component of the caveolae plasma membranes found in most cell types. The protein links integrin subunits ...
.
Ligands
; Agonists
* IRL-1620Bosentan
Bosentan, sold under the brand name Tracleer and Safebo among others, is a dual endothelin receptor antagonist medication used in the treatment of pulmonary artery hypertension (PAH).
Bosentan is available as film-coated tablets (62.5 mg o ...
(unselective ETA / ETB antagonist)
See also
* Endothelin receptor
There are at least four known endothelin receptors, ETA, ETB1, ETB2 and ETC, all of which are G protein-coupled receptors whose activation result in elevation of intracellular-free calcium, which constricts the smooth muscles of the blood vessels ...
References
Further reading
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External links
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{{DEFAULTSORT:Endothelin Receptor Type B
G protein-coupled receptors