Figure 4: (A) and (B) show the final models of H3 and H4.The ribbon color coding of TMs 1 to 7 is dark orange, pink, red, purple, dark red, orange and light yellow respectively, with ICLs and ECLs in dark green and the surface of receptor binding site in pink for H3 and green for H4. (B) The ICLs and ECLs are omitted to ease the view.