<prompt> Tetracyclines inhibit protein synthesis by acting on-30-S ribosome50-S ribosomeBoth 30-S 50-S ribosome60-S ribosome  <response>: Ans. is a i.e., 30-S ribosome Drugs binding to ribosome30-S ribosome50 -S ribosomeBoth 30-S 50-So Tetracyclineo Streptomycino Chloramphenicolo Erythromycino Clindamycino Aminoglycosides except streptomycinPleuromutilins Retapamulin new class of drug for topical treatment of impetigo due to MRSA and streptococcus. It acts by inhibiting protein synthesis after binding to 50 S ribosome. 