Fig. 4: DP1 activation mechanism.

a, b Comparison of the inactive (blue) and active (salmon) states of DP1, viewed within the plane of the membrane (a) and from the intracellular side (b). Red arrows indicate main conformational shifts of TMs on the intracellular side of the receptor. The membrane boundaries are shown in (a) as two gray lines. c–f Structural details of activation-related motifs in DP1, showing the ligand binding pocket (c), the T^5.52-L^3.43-F^6.44 motif (d), the sodium-binding site (e), the EC^3.50W and DP^7.50xxF motifs (f). The ligands in (a–f) are shown as sticks with carbon atoms colored in gold (PGD2) or cyan (ONO3030297). g MD analysis of K76^2.54 interactions with D72^2.50 and PGD2. h ONE-GO G_s signaling assay comparing the concentration-response signal induced by PGD2 at WT DP1 with activation-related mutants. The data are normalized to the basal signal (set at 0%) and the maximal PGD2-induced signal at WT DP1 (set at 100%). Data points correspond to means ± SEM for three biologically independent experiments conducted in triplicates. The corresponding E_max and EC₅₀ values are shown in Supplementary Table 2. Source Data are provided as a Source data file.