Although the structural information suggests that L11 should play a significant role in translation, functional analyses of the protein in this role have not been performed. In this report, a series of mutants were generated using a reverse genetics approach to parse the role of the L11 P-site loop. Detailed biochemical and structural analyses focused on two multi-amino acid mutants with opposing effects on rRNA structure and tRNA binding. We propose that prior to peptidyltransfer, the presence of peptidyl-tRNA in the large subunit P-site positions the L11 P-site loop to interact with the Helix 84 of the large subunit rRNA. After peptidyltransfer, spontaneous translocation of the deacylated tRNA to the large subunit E-site allows the L11 P-site loop to extend into the P-site, breaking contact with Helix 84. By this model, we hypothesize that the L11 P-site loop functions locally as a sensor of the occupancy status of the ribosomal P-site.