Bacterial 50S ribosomal subunit protein (50S ribosomal subunit (no standard protein abbreviation for the whole subunit; individual proteins have unique abbreviations, e.g., L5, L16, but usually the "50S ribosomal subunit" designation is used))

The **bacterial 50S ribosomal subunit protein** is the larger component of the prokaryotic (bacterial and archaeal) 70S ribosome. It consists of two main ribosomal RNA molecules (23S and 5S rRNA), alongside over 30 associated ribosomal proteins (33 in *E. coli*). The 50S subunit is pivotal in translation, catalyzing peptide bond formation and ensuring the correct elongation of the nascent polypeptide. It provides critical binding sites for tRNAs and translation factors responsible for the initiation, elongation, and termination steps of protein synthesis. Many antibiotics (macrolides, chloramphenicol, clindamycin, pleuromutilins, and more) exert their effect by binding the 50S subunit and blocking its function, making it a major therapeutic target for antibacterial drugs. Mutations in the 50S rRNA or proteins can lead to antibiotic resistance. The subunit itself is not a single protein but rather a ribonucleoprotein complex comprised of rRNAs and numerous proteins.

Other names

50S large ribosomal subunitLarge ribosomal subunit (prokaryotic/bacterial)Prokaryotic 50S ribosomal subunit

Inhibition of protein synthesis by binding to the 50S subunit, blocking peptidyl transferase activity or elongation/translocation functions