EF-P (eubacterial elongation factor P) is a highly conserved protein essen-tial for protein synthesis. We report that EF-P protects 16SrRNA near the G526 streptomycin and theS12 and mRNA binding sites (30ST-site). EF-P also protects domain V of the 23SrRNA proximal to the A-site (50ST-site) and more strongly the A-site of 70Sribosomes.