Figure 4. Cathepsin S and hexapeptide agonists increase the concentration of inositol phosphate.

IP1 is a downstreatm metabolite of IP3. IP1 concentrations were measured following treatment with cathepsin S, KVDGTS and SLIGRL in HeLa cells that had been transfected with PAR2 cDNA. Hexapeptide agonists activated this signaling cascade downstream of PAR2, but to a lesser extent than cathepsin S. Cathepsin S had no effect above baseline IP1 levels on salmon sperm transfected cells. Cathepsin S (1 µM), KVDGTS (100 µM) and SLIGRL (10 µM).