%0 Journal Article
%T Molecular cloning of the rat proteinase-activated receptor 4 (PAR4)
%A Willemijntje A Hoogerwerf
%A Helen Hellmich
%A Maria Micci
%A John H Winston
%A Lei Zou
%A Pankaj J Pasricha
%J BMC Molecular Biology
%D 2002
%I BioMed Central
%R 10.1186/1471-2199-3-2
%X The cDNA coding for the rat PAR4 homologue was cloned from the duodenum. Northern blots demonstrated a 3.0 kb transcript in the duodenum. Protein homology with mouse and human counterparts was 90% and 75% respectively. PAR4 is expressed predominantly in the esophagus, stomach, duodenum and the spleen. When expressed in COS cells, PAR4 is activated by trypsin (1 nM), thrombin (50 nM), mouse PAR4 specific peptide (500 ¦ÌM) and a putative rat PAR4 specific activating peptide (100 ¦ÌM), as measured by intracellular Ca2+-changes.We have identified and characterized cDNA encoding the rat PAR4 homologue. PAR4 is expressed predominantly in the upper gastrointestinal tract. It is activated by trypsin, thrombin and its newly identified rat PAR4 specific activating peptide.Proteinase-activated receptors (PARs) comprise a sub-family of G-protein coupled receptors, which are activated by serine proteases such as trypsin and thrombin. Cleavage of PARs unmasks an extracellular N-terminal domain that subsequently binds and activates the receptor, thus acting as a tethered ligand. Four related receptors have been identified to date [1-7]. Most recently, both human and mouse proteinase-activated receptor 4 (AR4) have been cloned [5,7]. Although best known for their role in the vascular and clotting systems, PARs have also been implicated as potential modulators of gastrointestinal motility [8-11] and recent studies have suggested a possible similar role for PAR4 [10]. However, to date, the rat PAR4 homologue has not been cloned and the tissue distribution of rat PAR4 in the gastrointestinal tract is unknown. In this report, we describe the cloning of a functional rat PAR4 cDNA. When expressed transiently in COS-1 cells, the rat PAR4 was activated by thrombin, trypsin, mouse PAR4 activating peptide and its own newly identified rat PAR4 tethered ligand. The rat PAR4 is mainly expressed in the rat esophagus, stomach, duodenum and the spleen.Primers, based upon the mouse PAR4 sequence, wer
%U http://www.biomedcentral.com/1471-2199/3/2