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SANS data from solutions of Glutamate receptor 2 (GluA2) in the AMPA bound state, at acidic pH in D2O based buffer. 10 mM AMPA, 20 mM Tris/DCl, 100 mM NaCl, 0.5 mM deuterated n-dodecyl-β-D-maltopyranoside (synthesized to match out at 100% D2O), pH 5.5 were collected on the KWS1 camera at the FRM2 storage ring (Munich, Germany) using a 6Li-Scintillator 1 mm thickness + photomultiplier detector at a wavelength of λ = 0.5 nm (l(s) vs s, where s = 4πsinθ/λ, and 2θ is the scattering angle). One solute concentration of 0.28 mg/ml was measured at 10°C. 15 successive 900 second frames were collected. The data were normalized to the intensity of the transmitted beam and radially averaged; the scattering of the solvent-blank was subtracted.
Sample of GluA2 in the AMPA bound state at acidic pH (pH 5.5). The SANS data were fitted with a mixture of GluA2 in a tetrameric loose form obtained with cryo electron microscopy (EM) by Meyersen et al. (Meyerson, J. R., Chittori, S., Merk, A., Rao, P., Han, T. H., Serpe, M., Mayer, M. L. & Subramaniam, S. (2016). Nature 537, 567-571) and oligomers of the tetramer (best fit: fit116.dat). The loose form was an atomic model fitted into a low resolution EM density map (EM class 3; EMD-2688). The oligomers were described with a fractal structure factor (Teixeira, J. (1988). J. Appl. Crystallogr. 21, 781-785). Data were fitted with WillItFit (Pedersen, M. C., Arleth, L. & Mortensen, K. (2013). J. Appl. Crystallogr. 46, 1894-1898). The SANS data were measured in three settings (sample/collimation): 1.5m/4m, 4m/4m, and 8m/8m. The attached data are merged into one data set with all three settings. Pair distance distribution functions were calculated with BayesApp (www.bayesapp.org). It was not feasible to perform a sensible Guiner analysis due to aggregation. Due to relatively low protein concentration, the concentration measurement was inaccurate, and the MW was therefore evaluated by (concentration independent) Porod analysis using the Porod volume calculator implemented in PRIMUS, and with a volume-to-mass conversion constant of 0.83 kDa/nm^3 (Gekko, K. & Noguchi, H. (1979). J. Phys. Chem. 83, 2706-2714; Squire, P. G. & Himmel, M. E. (1979). Arch. Biochem. Biophys. 196, 165-177).
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s, nm-1
