The EC50 of a ligand is its concentration that induces a half-maximal response by its cognate receptor. We plotted the highest value of the normalized fluorescence estimated in each of the aforementioned runs as a function of the concentration of VUAA1 in the sample and determined the EC50 for the activation of Orco by VUAA1 to be 0.85 mM and 0.41 mM for extracellular calcium concentrations of 1 mM and 5 mM, respectively (Figure 6 ).
Figure 6: EC50 for the interaction between VUAA1 and Orco is estimated to be 0.85 mM and 0.41 mM for extracellular calcium concentrations of 1 mM and 5 mM, respectively.
Although EC50 values of VUAA1 have not been explicitly determined inA. gambiae , they have been calculated for genetically engineered HEK293 cells and Xenopus oocytes that express Orco, albeit using electrophysiological measurements [32]. Not only is thePichia system equally sensitive as the HEK293 system, but it offers other advantages such as greater modularity, simpler optimization and easier deployment in an assay.
3.5. DMSO does not interfere with Orco in the assay