Fig. 5: Selected spectra and volumes of reconstructed EELS data of RyR1.
From: Elemental mapping in single-particle reconstructions by reconstructed electron energy-loss analysis
a, The spectrum of the sum of all intensities in the EELS reconstructions shows elemental edges for the most abundant elements: carbon, potassium, nitrogen and oxygen. The asterisks mark regions where the spectra show dips due to double-wide pixels at the tile boundaries of the detector, which are not perfectly accounted for by the detector’s flatfield correction. b, For the region between 121 and 240 eV, a background subtraction was performed, based on a fit of the spectrum between 121 eV and 127 eV. The subtracted spectrum shows additional edges for phosphorus and chlorine. c–e, Gaussian-filtered reconstructions for three 4.6 eV regions of the spectrum are shown together with an atomic model of rabbit RyR1, PDB-5TAQ ref. 24. Before the carbon edge (c), the reconstruction shows a uniform distribution of intensity between the protein and the solvent. At the carbon edge (d), the reconstruction shows colocalization with the protein and micelle, and at the oxygen edge (e), the reconstruction shows colocalization with the solvent. The reconstructions reflect the known local distributions of carbon and oxygen. f, The spectrum of summed intensities of a 4 × 4 × 4 voxel region at the known calcium-binding site does not show a calcium edge discernible above noise at 346, 350 eV. g, The spectrum of a single voxel within the protein shows a clearly discernible carbon edge. A background fit based on the region 120–240 eV is displayed for better visualization. The scale bar near c corresponds to 10 nm and applies to c–e.
