Additional file 9: Figure S9. of Quaternary structure of a G-protein-coupled receptor heterotetramer in complex with Gi and Gs

Positioning YFP in the C-tail of A2AR. The complex between the A2AR protomer (in light green) and Gs (α-subunit in dark grey and yellow, β-subunit in light gray, and γ-subunit in purple) was constructed from the crystal structure of β2 in complex with Gs [33]. Although the exact conformation of the A2AR C-tail (102 amino acids, Gln311–Ser412) cannot unambiguously be determined, its orientation was modeled as in the C-tail of squid rhodopsin [39], which contains the conserved amphipathic helix 8 that runs parallel to the membrane and an additional cytoplasmic helix 9. Thus, the C-tail of A2AR expands (see solid light green line) and points intracellularly toward the N-termini of the γ-subunit as suggested for OXER [32]. The laboratory of Kostenis has shown that the C-terminal of OXER, labeled with Rluc (OXER-Rluc), gets close to the N-terminal of the γ-subunit, labeled with GFP (γ-GFP) [32]. Analogously, we propose that YFP attached to the C-tail of A2AR is positioned near the N-termini of the γ-subunit (in purple). (TIF 2395 kb)