Supporting Information

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Fig. 7. Fourier shell correlation showing the successive increase in resolution of the Env structure as a function of the number of subtomograms. The resulting Fourier ring correlation coefficients (FRCC) are shown for averages resulting from 10, 20, 50, 100, and 418 particles. The particles are randomly chosen and derived from the dataset taken at 4-µm defocus. As shown for averaging from projections (1), averaging of tomograms leads to significant increase of resolution. Additionally, the FRCC for an average derived from the 321 particles that yielded the highest cross-correlation values are shown.

1. Böttcher, B., Wynne, S. A. & Crowther, R. A. (1997) Nature 386, 88-91

Fig. 8. Fourier ring correlation of two independent averages, each derived from half the collected Env particles. According to the “0.5” criterion the resolution of the Env average was about 2.7 nm. The “3σ” criterion indicated a slightly higher resolution.