(A) Distribution of our odorant panel in odor space. Odor space was estimated using 961 odorants (blue dots) in a multi-dimensional odor space was based on 32 optimized physicochemical descriptors (Haddad et al., 2008). The first and second principal components were used to plot this odor space in 2 dimensions. The 54 odorants in our panel are indicated by small red circles. The large red circle is a 2D representation of the 32D hypersphere that was centered on the center of mass of the odorants in the screening set and enclosed all 54 odorants with a radius of 10.3. A hypersphere enclosing all 961 odorants in the odor space had a radius of 18.5. B-E) Oocytes injected with cRNA encoding MOR14-3 (B), MOR26-3 (C), MOR263-3 (D), or MOR283-3 (E), as well as Gαolf and CFTR, were challenged with 15 sec applications of seven odorant mixtures containing the 54 odorants in our panel, followed by 1mM IBMX. Each mixture contained 7-8 odorants, each at a concentration of 30 μM (the odorant composition of each mixture is listed in Supplementary Table 1).