Fig. 2.

Intracellular calcium mobilization in response to GPR120S or GPR120L receptor activation. Peak intracellular calcium responses to increasing concentrations of OA, Myr, and GW9508 were measured from fluorescence changes in Fluo4 indicator-loaded 293TR cells expressing FLAG-GPR120S (A), FLAG-GPR120L (B), SNAP-GPR120S (C), and SNAP-GPR120L receptors (D). OA responses were also assessed in cells without prior tetracycline induction of receptor expression (No induction). Vehicle was medium containing 0.3% DMSO. The curve fits for FLAG- or SNAP-GPR120S GW9508 responses (from A or C) are also reproduced as dotted lines for comparison in the GPR120L graphs (B and D). Pooled data represent the mean ± S.E.M. of 3 to 13 experiments performed in triplicate, which yielded pEC₅₀ values quoted in the text. E, representative images of the cell surface expression of SNAP-GPR120S and SNAP-GPR120L receptors in induced 293TR cells (acquired on the IX Ultra plate reader after labeling with membrane-impermeant SNAP-AF488 dye, as Fig. 6). The average cellular fluorescence intensity was calculated from these images (see Data Analysis) as a guide to the relative expression levels of the two isoforms, and the resulting pooled data (n = 6) is shown in histogram F. *, P < 0.05 (unpaired Student's t test). RFU, relative fluorescence units.