Ribosome stalk region

The stalk region, present in all large ribosomal subunits, consists of at least one dimer of r-protein L12. It has been shown that two dimers of the L12 protein are bound to one molecule of LIO protein, which in turn binds to the large subunit r-RNA[117j. In E. coli, the second dimer of L12 is located in the body of the large ribosomal subunit at the base of the stalk [118]. The L12 proteins can be removed from the E. coli ribosome by salt/ethanol washes [119] either as the two dimers or in a pentameric complex with LIO. 

FIGURE 11 Bacterial ribosome structure at 7.8 A. Architectural features of Thermus thermophilus 70S ribosomes are labeled, as identified by X-ray crystallography. The 308 subunit is the front, darker portion, and consists of the head (H) connected to the platform (P) and body (B). Other features of the 308 subunit are the neck (N), spur (8P), shoulder (8), and contacts between the head and platform (a and b). The 508 subunit includes the protein LI stalk, central protuberance (CP), and L7/L12 region. [Reprinted with permission from Cate, J. A., Yusupov, M. M., Yusupova, G. Zh., Earnest, T. N., and Noller, H. F. (1999). X-ray crystal structures of 708 ribosome functional complexes. Science 285, 2095-2104. 1999 American Association for the Advancement of 8cience.l... 

Fig. 8.3 a Schematic representation of S. niminantium P22 protein and its mutants. Their activities to LDC/ODC are also indicated. SR-L and M-O represent S. ruminantium LDC/ODC and mouse ODC, respectively, b Amino acid sequence alignment of the C-terminal region of P22 with other prokaryotic LIO proteins. Amino acids identical to P22 are shaded. The a8 helix region involved in the stalk structure of L7/12 proteins in the 70S ribosome is indicated by the thick bar. Box A and Box B indicate segments crucial for binding to LDC/ODC in P22... 

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