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. Author manuscript; available in PMC: 2007 Dec 6.
Published in final edited form as: Mol Cell. 2007 Nov 9;28(3):434–445. doi: 10.1016/j.molcel.2007.08.026

Figure 4. Localization of RbfA on the 30S subunit, and comparison of the atomic structure of RbfA with the cryo-EM density map.

Figure 4

(A) Interpretation of the extra mass in terms of 30S subunit conformational change, involving 16S rRNA helices 44 and 45 (orange), and RbfA mass (red). The mass attributable to RbfA was derived after subtraction of the density corresponding to shifted positions of helices 44 (h44′) and 45 (h45′) from the total extra mass shown in Figure 2B. (B, C) Stereo representations of the fittings of (B) the X-ray crystallographic structure (CCF = 0.78) and (C) and the homology model (CCF = 0.79) of the T. thermophilus RbfA into the corresponding cryo-EM density. The asterisk (*) in panel B points to an unoccupied region of the cryo-EM density, due to absence of three amino acid residues and a different orientation of the tail in the X-ray structure. However, the same density region is nicely accounted for by the homology model (panel C). Thumbnails to the left of the panels depict the orientations of the 30S subunit, with body (b), head (h), and platform (p) identified.