Localization and potential roles of the human proteinase-activated receptors
| PAR1 | PAR2 | PAR3 | PAR4 | |
|---|---|---|---|---|
| Tissue distribution3-a (Northern blot analysis) | Brain, lung, heart, stomach, colon, kidney, testis | Prostate, small intestine, colon, liver, kidney, pancreas, trachea | Heart, kidney, pancreas, thymus, small intestine, stomach, lymph node, trachea | Lung, pancreas, thyroid, testis, small intestine, placenta, skeletal muscle, lymph node, adrenal gland, prostate, uterus, colon |
| Cellular expression | Platelets, endothelium, vascular smooth muscle, leukocytes, GI tract epithelium, fibroblasts, neurons, mast cells | Endothelium, leukocytes, GI tract epithelium and lung, airway and vascular smooth muscle, neurons, mast cells, keratinocytes, lung fibroblasts, renal tubular cells | Airway smooth muscle, platelets | Platelets, megakaryocytes |
| Known physiological role | Platelet activation | Platelet activation | ||
| Potential physiological roles | Pro-inflammatory, embryonic development, regulation of vascular tone | Pro-inflammatory, mediator of nocioception, airway protection, regulation of vascular tone | Cofactor for PAR4 | Platelet activation |
GI, gastrointestinal.
↵3-a  Information for PAR2, PAR3, and PAR4 is provided for human tissues; for PAR1, distribution is recorded in rat tissues, for which more extensive data are available than in human tissues.