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. 2007 Aug 7;5(8):e209. doi: 10.1371/journal.pbio.0050209

Figure 4. Chloroplast-Unique Structures Dominate the mRNA Exit Channel Area.

Figure 4

Solvent-exposed face of the small subunit is shown slightly turned to look at the mRNA exit channel.

(A) Stereo pair image. The largest chloroplast-unique structure on the ribosome, cuα (blue), emerges from the head and neck of the small subunit and partially defines the path of access for mRNA at the exit channel.

(B) cuα has been removed from this image to reveal the trough from the mRNA exit channel down into the midbody of the small subunit (dashed line). The platform is slightly lifted on the chloroplast ribosome, as indicated by the black arrows (arrows not to scale), accentuating the trough.

(C) E. coli ribosome cryoEM structure for comparison indicates the location of proteins known to be altered in the chloroplast ribosome along the path of the trough (S1, S2, and S5; see Figure S3).