Because two azithromycin molecules are bound to the co-crystal structure of the D. radiodurans ribosome, two molecules of 11 (11-1 and 11-2) were used in the generation of our homology models. Structures 11-1 and 11-2 are light blue and dark blue, respectively. RNA fragments are shown as orange tubes or gray surfaces, and L4 and L22 proteins are in green and yellow, respectively. Pymol1.0 was used to generate the figures. For details, see text.