Extended Data Fig. 2: Purification of BmGr9 and cryo-EM workflows.
From: The molecular basis of sugar detection by an insect taste receptor
a, Superose 6 elution profile of purified BmGr9. The majority of the protein elutes as a tetramer. b, Coomassie staining of denaturing and native gels confirm BmGr9 is a homotetramer with an effective molecular weight of approximately 700 kDa (including detergent micelle), similar to Orco13. Molecular weight markers are labeled for each gel (similar results were obtained from more than three independent purifications). c, A representative motion-corrected micrograph showing the distribution of fructose-bound BmGr9 single particles (scale bar, 50 nm). The numbers of micrographs and auto-picked particles are shown. d, Example two-dimensional class averages of particles selected for further processing. e, Fourier shell correlation (FSC) curves for the final cryo-EM density maps. Half-map FSC (with tight mask) (left), model-map FSC curves (right). The horizontal dashed line represents the FSC = 0.143 cutoff value. f, Local resolution of fructose-bound BmGr9 density map viewed from the top (top) and side (bottom). In side views, the nearest subunit has been removed to expose the pore. g-m, Equivalent data for unbound BmGr9 (g-j) and sorbose-bound Bmgr9 (k-n).
