The angiopoietin receptors are receptors that bind
angiopoietin.
TIE-1
Tyrosine kinase with immunoglobulin-like and EGF-like domains 1 also known as TIE1 is an angiopoietin receptor which in humans is encoded by the ''TIE1'' gene.
Function
TIE1 is a cell surface protein expressed exclusively in endothelial cells, ...
and
TIE-2
The angiopoietin receptors are receptors that bind angiopoietin.
TIE-1 and TIE-2 comprise the cell-surface receptors that bind and are activated by the angiopoietins, (Ang1, Ang2, Ang3, Ang4). The angiopoietins are protein growth factors r ...
comprise the cell-surface receptors that bind and are activated by the
angiopoietins
Angiopoietin is part of a family of vascular growth factors that play a role in embryonic and postnatal angiogenesis. Angiopoietin signaling most directly corresponds with angiogenesis, the process by which new arteries and veins form from pre ...
, (Ang1, Ang2, Ang3, Ang4). The angiopoietins are protein growth factors required for the formation of blood vessels (
angiogenesis
Angiogenesis is the physiological process through which new blood vessels form from pre-existing vessels, formed in the earlier stage of vasculogenesis. Angiogenesis continues the growth of the vasculature by processes of sprouting and splitting ...
).
Angiopoietins
The
angiopoietins
Angiopoietin is part of a family of vascular growth factors that play a role in embryonic and postnatal angiogenesis. Angiopoietin signaling most directly corresponds with angiogenesis, the process by which new arteries and veins form from pre ...
are
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, respo ...
growth factors
A growth factor is a naturally occurring substance capable of stimulating cell proliferation, wound healing, and occasionally cellular differentiation. Usually it is a secreted protein or a steroid hormone. Growth factors are important for regu ...
that regulate
angiogenesis
Angiogenesis is the physiological process through which new blood vessels form from pre-existing vessels, formed in the earlier stage of vasculogenesis. Angiogenesis continues the growth of the vasculature by processes of sprouting and splitting ...
, the formation of blood vessels. In humans, three angiopoietins have been identified: Ang1, Ang2, and Ang4 (Ang 3 is the mouse ortholog of human Ang4).
Ang1 and Ang4 function as agonistic or activating ligands for Tie2, whereas Ang2 and Ang3 behave as competitive antagonists. They function by binding their physiologic receptors, Tie-1 and Tie-2. These are receptor
tyrosine kinases
A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to the tyrosine residues of specific proteins inside a cell. It functions as an "on" or "off" switch in many cellular functions.
Tyrosine kinases belong to a larger cla ...
, so named because they mediate cell signals by inducing the phosphorylation of key tyrosines, thus initiating
cell signalling
In biology, cell signaling (cell signalling in British English) or cell communication is the ability of a cell to receive, process, and transmit signals with its environment and with itself. Cell signaling is a fundamental property of all cellula ...
.
It is somewhat controversial which of the Tie receptors mediate functional signals downstream of Ang stimulation. But it is clear that at least Tie-2 is capable of physiologic activation as a result of binding the angiopoietins.
See also
*
Angiopoietin#Tie pathway
External links
*
References
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Tyrosine kinase receptors
Developmental neuroscience