Endothelin receptor type B

Endothelin receptor type B, also known as ETB is a is_associated_with::protein that in humans is encoded by the EDNRB is_associated_with::gene.

Function
Endothelin receptor type B is a is_associated_with::G protein-coupled receptor which activates a phosphatidylinositol-calcium second messenger system. Its ligand, is_associated_with::endothelin, consists of a family of three potent vasoactive peptides: ET1, ET2, and ET3. 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 ET1, they exhibit different responses upon binding which suggests that they may be functionally distinct.

Regulation
In melanocytic cells the EDNRB gene is regulated by the is_associated_with::microphthalmia-associated transcription factor. Mutations in either gene are links to is_associated_with::Waardenburg syndrome.

Clinical significance
The multigenic disorder, is_associated_with::Hirschsprung disease type 2, is due to mutation in endothelin receptor type B gene.

In is_associated_with::horses, a mutation in the middle of the EDNRB gene, Ile118Lys, when is_associated_with::homozygous, causes is_associated_with::Lethal White Syndrome. In this mutation, a mismatch in the is_associated_with::DNA replication causes is_associated_with::isoleucine to be made instead of is_associated_with::lysine. 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 is_associated_with::heterozygous state, produces an identifiable and completely benign spotted coat color called frame overo.

Interactions
Endothelin receptor type B has been shown to interact with is_associated_with::Caveolin 1.