Fig. 6

ssNMR characterization of phospholipids co-purified with MelB_St. a–c Cut-outs from 2D PARIS ¹³C-¹³C PARIS spin diffusion ssNMR spectra of MelB_St, which were measured at 265 K (panels a or c) or 308 K (panel b) sample temperature, and with 40 ms mixing time. The correlations of glycerol backbones (red in panel a and b), anionic headgroups (orange in panel a and b), and the tail carbons (cyan in panel c) of the endogenous lipids, are illustrated. d A 2D PARIS-xy ¹³C-¹³C ssNMR spectrum with a mixing time of 160 ms shows clear correlations between lipid glycerol backbone and lipid tail carbons. Illustrative carbon-carbon connectivities are highlighted with blue-dashed lines. e Cut-out of the lipid headgroup region of a 2D ¹³C-¹³C PARIS ssNMR spectrum of reconstituted, membrane-embedded K⁺ channel KcsA, which was purified from E. coli cells. The correlations (69–72 ¹³C ppm) from the headgroups of endogenous, co-purified anionic lipids, which are assumed to be PG headgroups [29, 47], are indicated. f Overlay of a 2D PARIS spectrum of MelB_St on KcsA