show Abstracthide AbstracttRNA undergoes post-transcriptional modifications by site-specific tRNA modification enzymes. Recent RNA sequencing techniques allow ones to analyze in vivo tRNA behavior such as tRNA abundance. Here, we adapt a tRNA sequencing technique. During reverse transcription, some RNA modifications induce nucleotide misincorporation into the cDNA, which is recorded as elevated mutation rates in next-generation sequencing. Using tRNA mutational profiling, we design a new tRNA-related enzymological analysis to gain mechanistic insights into how tRNA modification enzymes recognize substrate tRNA.