FIGURE 2.

Key interactions between OR and G-Proteins. Only common interactions between the four receptors were depicted. The Ballesteros-Weinstein (BW) numbering scheme, which allows the comparison of any amino acid residue in the structurally conserved TM helices of GPCRs, was used. For ICL2, residues were labeled 34. X, indicating the positions between TM3 and TM4. X.50 was once again attributed to the most conserved residue. DOR residues numbers were used for ICL3 numbering, since this substructure is not conserved among OR.