Prokaryotic large ribosomal subunit

Atomic structure of the 50S Subunit from Haloarcula marismortui. Proteins are shown in blue and the two RNA strands in orange and yellow.[1] The small patch of green in the center of the subunit is the active site.
Atomic structure of the 50S large subunit of the ribosome, facing the 30S small ribosomal subunit. Proteins are colored in blue and RNA in ochre. The active site, adenine 2486, is highlighted in red. Image created from PDB: 3CC2​ using PyMol

50S is the larger subunit of the 70S ribosome of prokaryotes, i.e. bacteria and archaea. It is the site of inhibition for antibiotics such as macrolides, chloramphenicol, clindamycin, and the pleuromutilins. It includes the 5S ribosomal RNA and 23S ribosomal RNA.

Despite having the same sedimentation rate, bacterial and archaeal ribosomes can be quite different.

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