Table 1 Effects of mutation of residues flanking the central binding site on ionone binding. (measured as threshold, i.e. a 10% signalling output level of 10 µM forskolin) and subsequent maximal receptor activation (Emax, see Fig. S3 for details) ± SEM by 250 μM (normalized to wild type; n = 4–15). Colour coding: hyperactive mutants (Emax > 110% of WT) in green; unaffected mutants (threshold 170–140 µM and Emax 110–80% of WT) in white; affected mutants (threshold 210–170 µM and Emax 80–40% of WT) in yellow; inactive mutants (threshold >210 µM and Emax <40% of WT) in orange. A decrease in Emax is coupled to an increase in threshold concentration. Mutations to Ala in silico of the respective residues that lead to a significant change in ΔΔGbind mostly corresponds to an alteration of activation in experiment, as well. The control mutant residue I2556.52 does not exhibit a significant influence on ligand binding.
