Interactions of the TnaC nascent peptide with rRNA in the exit tunnel enable the ribosome to respond to free tryptophan.
Martínez AK, Gordon E, Sengupta A, Shirole N, Klepacki D, Martinez-Garriga B, Brown LM, Benedik MJ, Yanofsky C, Mankin AS, et al. Nucleic Acids Res. 2014 Jan; 42(2):1245-56. Epub 2013 Oct 16.