targeted_by targeted_by_antibiotic erythromycin roxithromycin streptogramin B antibiotic telithromycin clarithromycin linezolid targeted_by targeted_by_antibiotic oxazolidinone antibiotic tylosin spiramycin azithromycin dirithromycin thiostrepton 50S ribosomal subunit 50S ribosomal subunit P-site ARO:3000757 antibiotic_resistance The P-site of the ribosome binds the peptidyl-tRNA with the growing polypeptide chain, and is a common target for many antibiotics that inhibit the 50S ribosomal subunit. Some antibiotics (oxazolidinones) block the 50S subunit from interacting with the 30S subunit to prevent the formation of the ribosomal complex. Other antibiotics (thiostrepton) block the 50S subunit from interacting with elongation factors G and Tu (EF-G, Ef-Tu), preventing GTP-dependent reactions of peptidyl transferase, and translocation, respectively. Other antibiotics (macrolides) prevent protein translocation.