S4, S5, and S12, along with H18, are located near the channel where mRNA is present in the 30S subunit. Inhibition The 30S subunit is the target of antibiotics such as tetracycline and gentamicin. These antibiotics specifically target the prokaryotic ribosomes, hence their usefulness in treating bacterial infections in eukaryotes. Tetracycline interacts with H27 in the small subunit as well as binding to the A-site in the large subunit. Puromycin is an inhibitor of ribosomal translation. Pactamycin interrupts the binding in the Shine-Dalgarno binding region in the small subunit, thus disrupting activity. Hygromycin B also interacts with H44 and inhibits the translocation movement that is necessary during protein synthesis. See also Prokaryotic large ribosomal subunit (50S) Ribosomal RNA Antibiotics References External links 16S rRNA, BioMineWiki http://pathmicro.med.sc.edu/mayer/antibiot.htm Ribosomal RNA Protein biosynthesis