PT  - JOURNAL ARTICLE
AU  - Bahjat Al-Ani
AU  - Mahmoud Saifeddine
AU  - Atsufumi Kawabata
AU  - Bernard Renaux
AU  - Shalini Mokashi
AU  - Morley D. Hollenberg
TI  - Proteinase-Activated Receptor 2 (PAR<sub>2</sub>): Development of a Ligand-Binding Assay Correlating with Activation of PAR<sub>2</sub> by PAR<sub>1</sub>- and PAR<sub>2</sub>-Derived Peptide Ligands
DP  - 1999 Aug 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 753--760
VI  - 290
IP  - 2
4099  - http://jpet.aspetjournals.org/content/290/2/753.short
4100  - http://jpet.aspetjournals.org/content/290/2/753.full
SO  - J Pharmacol Exp Ther1999 Aug 01; 290
AB  - A cloned rat proteinase-activated receptor (PAR)2-expressing cell line (KNRK-rPAR2) was used to study the structure-activity relationships (elevated intracellular Ca2+) for a series of: 1) PAR1-derived receptor-activating ligands (PAR1-APs) [SFLLR (P5), SFLLR-NH2(P5-NH2), SFLLRNP (P7), SFLLRNP-NH2(P7-NH2), and TFLLR-NH2 (TF-NH2)] and 2) PAR2-derived-activating-peptides (PAR2-APs) [SLIGRL-NH2 (SL-NH2), SLIGR-NH2 (GR-NH2), and SLIGKV-NH2(KV-NH2)]. The activities of the PAR-APs were compared with the PAR2-AP analogtrans-cinnamoyl-Leu-Ile-Gly-Arg-Leu-Orn-NH2tc-NH2), which as a [3H]propionyl derivative ([3H]propionyl-tc-NH2) was used to develop a radioligand-binding assay for PAR2. The relative potencies of the PAR-APs in the Ca2+-signaling assay were tc-NH2 = SL-NH2 > KV-NH2≅ P5-NH2 > GR-NH2 > P7-NH2 > P7 > P5 > TF-NH2. The reverse sequence PAR-APs, LSIGRL-NH2(LS-NH2), LRGILS-NH2 (LR-NH2), FSLLRY-NH2 (FSY-NH2), and FSLLR-NH2(FS-NH2), as well as the XenopusPAR1-AP TFRIFD-NH2, were inactive. The relative biological potencies of the peptides were in accord with their ability to compete for the binding of [3H]propionyl-tc-NH2 (tc-NH2= SL-NH2 > GR-NH2 ≅ P5-NH2 > P5) to KNRK-rPAR2 cells, whereas inactive peptides (FS-NH2; LR-NH2) showed no appreciable binding competition. Our data therefore validate a ligand-binding assay for the use in studies of PAR2 and indicate that the relative biological potencies of the PAR1-APs for activating rat PAR2 parallel their ability to activate human PAR1. The relative receptor-binding activities of the PAR-APs, although in general agreement with their relative biological activities, point to differences in the intrinsic receptor-activating activities between the several PAR-APs. The binding assay we have developed should prove of use for the further study of PAR2-ligand interactions. The American Society for Pharmacology and Experimental Therapeutics