Isotope labelled 2-Methylthio-N6-isopentenyladenosine is located at position 37 in tRNAs that read codons starting with uridine. 2-Methylthio-N6-isopentenyladenosine in trpT(Su9) suppressor tRNA increase the efficiency of the tRNA by protecting it from ribosomal proofreading which is induced by codon context.
