Fig. 4.

Analysis of G_sα conformation and its possible partial dissociation from β₂AR based on all-atom MD Anton runs. The distances and angle shown in each run are based on their average values during the last 2 μs of MD simulations. The distances and angles were measured between geometric centers of protein residues or domains. (A) A161–E299 distances indicating G_s protein conformational change (opening or closing), G_sαAH–G_sαRas distances indicating relative movement between the two domains, the angle between the two vectors of G_sαAH and G_sαRas domains indicating their relative orientation (B) α1–α5 distances indicating relative movement between α1 and α5 helices in G_sα, β₂AR–α5 distances indicating possible partial dissociation of G_sα α5 helix from the receptor, and β₂AR NPxxY motif–α5 helix distances also indicating G_sα α5 partial dissociation. (C) Illustration of the angle between G_sαAH and G_sαRas domains; vector 1 goes through G_sαAH and A161 centers; vector 2 goes through G_sαRas and E299 centers. (D) Illustrations of G_sα α5 helix (yellow), α1 helix (cyan), and β₂AR NPxxY motif (blue helix on transmembrane domain 7).