Protease-activated receptor

Protease-activated receptor

coagulation factor II (thrombin) receptor
Symbol F2R
Alt. symbols PAR1
Entrez 2149
HUGO 3537
OMIM 187930
RefSeq NM_001992
UniProt P25116
Other data
Locus Chr. 5 q13
coagulation factor II (thrombin) receptor-like 1
Symbol F2RL1
Alt. symbols PAR2, GPR11
Entrez 2150
HUGO 3538
OMIM 600933
RefSeq NM_005242
UniProt P55085
Other data
Locus Chr. 5 q13
coagulation factor II (thrombin) receptor-like 2
Symbol F2RL2
Alt. symbols PAR3
Entrez 2151
HUGO 3539
OMIM 601919
RefSeq NM_004101
UniProt O00254
Other data
Locus Chr. 5 q13
coagulation factor II (thrombin) receptor-like 3
Symbol F2RL3
Alt. symbols PAR4
Entrez 9002
HUGO 3540
OMIM 602779
RefSeq NM_003950
UniProt Q96RI0
Other data
Locus Chr. 19 p12

Protease-activated receptors are a subfamily of related G protein-coupled receptors that are activated by cleavage of part of their extracellular domain. They are highly expressed in platelets, but also on endothelial cells, myocytes and neurons.[1]


  • Classification 1
  • Activation 2
  • Function 3
  • References 4
  • External links 5


There are 4 known protease-activated receptors or PARs, numbered from one to four. These receptors are members of the seven transmembrane G-protein-coupled receptor superfamily, and are expressed throughout the body.


PARs are activated by the action of serine proteases such as thrombin (acts on PARs 1, 3 and 4) and trypsin (PAR 2).[2] These enzymes cleave the N-terminus of the receptor, which in turn acts as a tethered ligand. In the cleaved state, part of the receptor itself acts as the agonist, causing a physiological response.

Most of the PAR family act through the actions of G-proteins i (cAMP inhibitory), 12/13 (Rho and Ras activation) and q (calcium signalling) to cause cellular actions.


The cellular effects of thrombin are mediated by protease-activated receptors (PARs). Thrombin signalling in platelets contributes to hemostasis and thrombosis. Endothelial PARs participate in the regulation of vascular tone and permeability while in vascular smooth muscle they mediate contraction, proliferation, and hypertrophy. PARs contribute to the pro-inflammatory response observed in atherosclerosis and restenosis. Recent research has also implicated these novel receptors in muscle growth and bone cell differentiation and proliferation.[3]

In T cells, activation of PAR1, PAR2 and PAR3 induce tyrosine phosphorylation of VAV1. Activation of PARs also led to an increase in tyrosine phosphorylation of ZAP-70 and SLP-76, two key proteins in T cell receptor (TCR) signalling.[4]


  1. ^ Macfarlane SR, Seatter MJ, Kanke T, Hunter GD, Plevin R (2001). "Proteinase-activated receptors" (abstract). Pharmacol Rev 53 (2): 245–82.  
  2. ^ Coughlin SR, Camerer E (January 2003). "PARticipation in inflammation". J. Clin. Invest. 111 (1): 25–7.  
  3. ^ Martorell L, Martínez-González J, Rodríguez C, Gentile M, Calvayrac O, Badimon L (February 2008). "Thrombin and protease-activated receptors (PARs) in atherothrombosis". Thromb. Haemost. 99 (2): 305–15.  
  4. ^ Bar-Shavit R, Maoz M, Yongjun Y, Groysman M, Dekel I, Katzav S (January 2002). "Signalling pathways induced by protease-activated receptors and integrins in T cells". Immunology 105 (1): 35–46.  

External links

  • "Protease-Activated Receptors". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. 
  • Proteinase-Activated Receptors at the US National Library of Medicine Medical Subject Headings (MeSH)