Dose–response of raw fluorescence changes of HEK293 cells transfected with BmGr9 and GCaMP (filled circles) or GCaMP alone (open circles) when titrated with d -fructose (left) or l -sorbose (right). d -Fructose data are best fitted by an EC 50 of 8.2 (5.9–11.5) mM with a Hill coefficient of 2.3 (1.3–4.6) ( n = 8 independent samples; points are mean ± s.e.m.; fitted 95% confidence intervals are given in parentheses). For l -sorbose ( n = 5 independent samples), the maximum activity is less than that for control wells with GCaMP alone.
