PAR2 is a
member of the large family of 7-transmembrane-region receptors that couple to guanine nucleotide-binding proteins.
The physiologic activator at this receptor is apparently not activated by ordinary ligand binding but by
proteolytic cleavage of its extracellular amino terminus. The cleavage leaves the new amino terminus, a tethered ligand,
free to interact with some other region of the receptor, presumably to effect receptor activation. PAR2 shares this special mode of activation with the thrombin receptor.
NCBI Summary:
Coagulation factor II (thrombin) receptor-like 1 (F2RL1) is a member of the large family of 7-transmembrane-region receptors that couple to guanosine-nucleotide-binding proteins. F2RL1 is also a member of the protease-activated receptor family. It is activated by trypsin, but not by thrombin. It is activated by proteolytic cleavage of its extracellular amino terminus. The new amino terminus functions as a tethered ligand and activates the receptor. The F2RL1 gene contains two exons and is widely expressed in human tissues. The predicted protein sequence is 83% identical to the mouse receptor sequence.
General function
Receptor
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Cellular localization
Plasma membrane
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Ovarian function
fertilization
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Expression regulated by
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Ovarian localization
Oocyte
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Tomlinson J, et al 2000 presented evidence for the activation of PAR-2 by the sperm protease,
acrosin and expression of the receptor on oocytes.
Proteinase-activated receptor-2 (PAR-2) is a member of a family of
G-protein-coupled, seven-transmembrane domain receptors that are activated by
proteolytic cleavage. The receptor is expressed in a number of different
tissues and potential physiological activators identified thus far include
trypsin and mast cell tryptase, Acrosin, a trypsin-like serine proteinase
found in spermatozoa of all mammals, was found to cleave a model peptide
fluorescent quenched substrate representing the cleavage site of PAR-2. This
substrate was cleaved with kinetics similar to those of the known PAR-2
activators, trypsin and mast cell tryptase. Immunohistochemical studies using PAR-2 specific antibodies
indicated that the receptor is expressed by mouse oocytes, which suggests that
acrosin may play additional role(s) in the fertilization process via the
activation of PAR-2 on oocytes.