50S ribosomal subunit

The large subunit of bacterial 70S ribosomes, built from 23S and 5S ribosomal RNA and proteins. It positions transfer RNAs and catalyzes peptide-bond formation.

23S ribosomal RNA: The large ribosomal RNA molecule that forms the core of the bacterial 50S subunit and catalyzes peptide-bond formation. Its peptidyl transferase center performs the subunit’s central catalytic reaction.
5S ribosomal RNA: A small ribosomal RNA molecule found in the large subunits of many ribosomes. It is one of the two ribosomal RNA molecules in the bacterial 50S subunit.
Chloramphenicol: An antibiotic that inhibits bacterial protein synthesis by binding the large ribosomal subunit. It blocks peptide-bond formation at the 50S peptidyl transferase center.
60S ribosomal subunit: The large subunit of eukaryotic cytosolic ribosomes, containing 28S, 5.8S, and 5S ribosomal RNAs. It performs the analogous large-subunit role in eukaryotes but differs in composition and structure.
Peptidyl transferase center: The ribosomal active site where peptide bonds form between amino acids attached to transfer RNAs. This catalytic center lies in the 50S subunit and is formed chiefly by 23S ribosomal RNA.
Ribosomal protein L2: A conserved large-subunit ribosomal protein that binds ribosomal RNA and contributes to subunit architecture. L2 is a prominent protein component positioned near the 50S catalytic center.
Macrolide antibiotics: A class of antibiotics that includes erythromycin and azithromycin and inhibits bacterial translation. Macrolides bind within the 50S exit tunnel and obstruct protein synthesis.
Mitochondrial ribosome: A ribosome inside mitochondria that synthesizes proteins encoded by mitochondrial DNA. Mitochondrial ribosomes have distinct structures and antibiotic sensitivities despite their bacterial ancestry.
Ribosomal exit tunnel: A passage through the large ribosomal subunit that newly synthesized polypeptides traverse as they emerge. The growing protein chain leaves the 50S subunit through this tunnel.
Ribosomal protein L3: A large-subunit ribosomal protein that helps organize ribosomal RNA near the peptidyl transferase center. L3 supports the RNA architecture surrounding the 50S active site.

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