Table I.

Microscopy, image reconstruction, and modeling data

Sample	Micrograph focal pairsa	Pixel size (Å)	Particle imagesb	CTF correctionc	Resolu tiond (Å)	EMDB IDe	PDB IDf
160S-C3	6	1.82	4184	full	11.1	5291	3J3O
135S-C3	2	1.84	9810	full	9.1	5292	3J3P
80S-C3g	7	1.84	238	phases only	22	5293	----

^aPairs of micrographs taken of the same field-of-view and used to compute 3D reconstructions, first image taken closer-to-focus, second image farther-from-focus. The 135S-C3 micrographs contained many more particles per micrograph than did micrographs of 160S-C3 complexes. Therefore, only two micrograph pairs were needed to compute the 135S-C3 structure.

^bTotal number of particle images extracted from micrographs and used to compute the 3D reconstruction, divide by two for the number of image pairs (focal pairs).

^cCorrection for the final, published reconstruction: full, deconvolution of CTF and correction for decay (see Materials and Methods); or, phases-only, corrected only for the phase-flipping effects of the CTF.

^dData set split in two, reconstructions computed and compared via Fourier shell correlation. Resolution determined by the point at which the Fourier shell correlation value reaches 0.5, for reconstructions computed from images that were only corrected for phase-flipping of the CTF.

^eIdentification code of density map in EM Data Bank.

^fProtein Data Bank identification code for coordinate modeling results.

^gSee Fig. S1 and Video 3. 80S particles were present in the 135S sample (cf. (15) and were used to compute the 80S-C3 reconstruction. More micrograph pairs were needed than were used for the 135S reconstruction because so few 80S particles were present per micrograph (see Fig. 2A).