Figure 5. Gene structures of different P2Y receptors from different vertebrates depicting novel intron insertions in P2Y2, P2Y3L and P2Y6 receptors from selected ray finned fishes.

There are three intron inserted at positions 124a, 181c and 267a (human MC5R amino acid numbering with suffix a–c for intron phasing) in P2Y2 receptors of four ray-finned fishes (Takifugu, Tetraodon, stickleback and medaka). There is one intron inserted at position 187c in P2Y3L of same fishes and there is one each species-specific intron S212a (stickleback; red arrow), M (medaka; blue) and T (Takifugu; green). The intron at position 120c is found in P2Y6 receptors of these fishes. These introns are not found in any other P2Y receptors from zebrafish, elephant shark and tetrapods. Transmembrane regions are marked as TM1–7 as predicted by TMHMM2.0 [106]. * indicates that novel P2Y3L is missing in Tetraodon genome. # indicates that P2Y6 receptor was not found in current assembly of elephant shark (C. milli).