Fig. 1.

Trypsin does not activate calcium signaling in the TL-mutant PAR₂ receptors as it does in wt-rPAR₂: comparison with activation by SLIGRL-NH₂. A, concentration-effect curves for trypsin-triggered calcium signaling. Receptor-expressing KNRK cell lines (■, wt-PAR₂; ●, rPAR₂-Ala^37–38; ♦, rPAR₂-Leu³⁷Ser³⁸; □, pcDNA3) were exposed to trypsin at increasing concentrations and the elevation of intracellular calcium relative to the signal caused by 1 μM A23187 (% A23187) was monitored as described under Materials and Methods. Trypsin concentration-effect curve for calcium signaling (A) and calcium signaling (% A23187) (B) triggered by SLIGRL-NH₂ (300 μM) in wt-rPAR₂ (■), rPAR₂-Leu³⁷Ser³⁸ (♦), and rPAR₂-Ala^37–38 (●) transfected KNRK cells. Values at each trypsin concentration (A) and in the histograms (B) represent the averages (± S.E.M., bars) for three or more independently conducted experiments.