title: Proteinase-activated receptor-2 in rat aorta: structural requirements for agonist activity of receptor-activating peptides.
abstract: We measured in rat aorta rings the relaxant activity of a number of peptides derived from the activating sequence (SLIGRL, or PP6) of the proteinase-activated receptor-2 (PAR-2). The relaxant action of PP6-NH2 mimicked the action of low concentrations of trypsin (0.5-1 unit/ml; 1-2 nM), was dependent on an intact endothelium, and was blocked by N-omega-nitro-L-arginine methyl ester but not by N-omega-nitro-D-arginine methyl ester. The relaxant actions of PP6, SLIGRL-NH2 (PP6-NH2), SLIGR (PP5), and SLIGR-NH2 (PP5-NH2) were comparable in magnitude, with relative potencies of PP6-NH2 > or = PP6 > PP5-NH2 > PP5. Peptides lacking either a leucine at position 2 (SAIGRL) or an arginine at position 5 (SLIGAL) exhibited markedly reduced or no relaxant activity; nevertheless, the tetrapeptide LIGR-NH2 exhibited low but detectable intrinsic activity. With the use of reverse-transcriptase/polymerase chain reaction, we documented the presence of PAR-2 mRNA in aorta tissue and determined that the rat aorta amino-terminal receptor-activating sequence was the same as that reported for the murine PAR-2 receptor. We concluded that the rat aorta tissue has a PAR-2 receptor that can be activated by peptides as short as four amino acids; the leucine and arginine at positions 2 and 5, respectively, of the proteolytically revealed PAR-2 receptor-activating sequence play key roles in regulating receptor function.
authors.affiliation: Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Calgary, Alberta, Canada.
authors.forename: M D
authors.initials: MD
authors.lastname: Hollenberg
authors.forename: M
authors.initials: M
authors.lastname: Saifeddine
authors.forename: B
authors.initials: B
authors.lastname: al-Ani
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D001483:Base Sequence; D001665:Binding Sites; D017931:DNA Primers; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley; D044464:Receptor, PAR-2; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D018179:Receptors, Thrombin / Q000032:analysis / Q000096:biosynthesis; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D009842:Oligopeptides; D010446:Peptide Fragments; D044464:Receptor, PAR-2; D011956:Receptors, Cell Surface; D018179:Receptors, Thrombin