Fig. 5: NMR structural comparison of isoprenaline-bound β₁AR ternary complexes with canonical and non-canonical G proteins.

a Spectral overlay of β₁AR-E-L289M^6.34 in complex with mini-G_s (blue) or mini-G_o1 (orange). b Similar comparison of G_i/o family complexes with β₁AR-E-L289M^6.34 bound to mini-G_i1 (magenta) or mini-G_o1 (orange). The global resemblance of the NMR structural fingerprints provides evidence of strong structural similarity amongst the ternary complexes. However, local differences become obvious in close-ups of specific regions of the receptor (c, d) in complex with mini-G_s (blue), mini-G_o1 (orange), mini-G_i1 (magenta) or the chimera proteins mini-G_s/i (red), mini-G_s/q (green): c focus on the region with M153^34.57 in IL2 and M296^6.41 on TM6; d close-up of L289M^6.34 on TM6. With the exception of the less stable mini-G_i1 (8 molar equivalents) all mini-G proteins were added at 2 molar equivalents. e 1D ¹⁹F NMR spectra of β₁AR-E ^TETC344^7.54 in ternary complex with isoprenaline and either mini-G_s (blue), mini-G_o1 (orange), mini-G_s/i (red) or mini-G_s/q (green) reveal differences in the TM7/IL4 region. The signal positions related to the ternary complexes (T) and agonist-only bound receptor (Iso.) are indicated by lines.