The 23SrRNA is a 2904 nt long (in E. coli) component of the large subunit (50S) of the bacterial ribosome. The ribosomal peptidyl transferase activity resides in domain V of this rRNA, and this domain is the most common binding site for antibiotics that inhibit translation. A well-known member of this antibiotic class, chloramphenicol, acts by inhibiting peptide bond formation, with recent 3D-structural studies showing two different binding sites depending on the species of ribosome. Linezolid and quinupristin-dalfopristin also bind to the 23S rRNA, and cross-resistance has been demonstrated between these antibiotics.
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^Halic M, Blau M, Becker T, Mielke T, Pool MR, Wild K, Sinning I, Beckmann R (2006). "Following the signal sequence from ribosomal tunnel exit to signal recognition particle.". Nature444 (7118): 507–11. doi:10.1038/nature05326. PMID17086193.