A family of unusual G-protein-coupled receptors (PARs) that are activated by cleavage of part of the extracellular domain: the cleaved fragment then acts as a ligand. PAR1 and PAR4 are thrombin receptors, PAR2 responds to trypsin but not thrombin and is up-regulated in chronic inflammation. PAR3 does not signal but acts as a cofactor for the cleavage and activation of PAR4. NB The abbreviation PAR4 has also been used for prostate apoptosis response protein-4.
Subjects: Medicine and Health.