The 23S rRNA is a 2,904 nucleotide long (in E. coli) component of the large subunit (50S) of the bacterial/archean ribosome and makes up the peptidyl transferase center (PTC).

[2] 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.

Numerous mutations in domains of the 23S rRNA with Peptidyl transferase activity have resulted in antibiotic resistance.

[4] 23S rRNA genes typically have higher sequence variations, including insertions and/or deletions, compared to other rRNAs.

However, 23S rRNA positions (G2252, A2451, U2506, and U2585) have a significant function for tRNA binding in the P site of the large ribosomal subunit.