Figure 4
IP3 simulations with differential receptor numbers. (a) IP3 experimental results (orange dots with SD) and simulations (blue curves) after Thrombin activation. (b) simulations of the impact of Gαq-coupled receptor numbers (RGq) on IP3 production. RGq numbers reflect primary and secondary GPCR ligand activation (Thrombin followed by TxA2 and ADP: RGq = 5,000; TxA2 followed by secreted ADP: RGq = 1,650; ADP alone: RG1 = 150). Activations occur at 100 s. (c) comparison of known IP3 and calcium mobilization results in platelets. in absence of experimental data on IP3 production after TxA2 activation, we are using known cytosolic calcium concentrations as a proxy27. The simulations of IP3 release from a receptor number corresponding to a TxA2/ADP activation (RGq = 1,650) show an intermediate response as is also seen for calcium mobilization experimental data.
