Crucial amino-acid interactions and conformational changes within G protein coupling domains.

<p>The backbone of D2R is shown as ribbons, whereas important amino acids are highlighted as sticks. The snapshots provided represent average structures taken from 950–975 ns (dopamine), 750–775 ns (aripiprazole) and 350–375 ns (FAUC350). (A–C) Crucial interactions between residues from the C-terminal part of Gα (Asp350, Phe354) and residues from the DRY-motif of TM3 (Asp^3.49, Arg^3.50), from IL2 (Met140, Tyr142) and from TM6 (Lys^6.28, Met^6.36) within representative snapshots of dopamine-, aripiprazole- and FAUC350-complexes are depicted in red, grey and blue, respectively. (D) A superposition of representative snapshots of dopamine-, aripiprazole- and FAUC350-complexes, represented in red, grey and blue, respectively, indicates conformational changes for residue Met140 of IL2 and for the N-terminal part of IL3. (E) Enlarged view of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100069#pone-0100069-g004" target="_blank">Figure 4d</a> on the conformational changes of residue Met140 of IL2 within the simulation systems. A green arrow visualizes the movement of residue Met140. (F) A superposition of representative snapshots of dopamine-, aripiprazole- and FAUC350-complexes, represented in red, grey and blue, respectively, highlights the increasing distance of the intracellular part of TM3 and the junction of TM7 and H8, measured as the distance between the Cα-atoms of Ala135^3.53 and Ile431 of TM7/H8 (dashed box).