Gogakos, T. et al. Cell Rep. 20, 1463–1475 (2017).
tRNAs are one of the classic models for noncoding RNAs. Decades of research have explored their role in translation; more recently, however, this role has expanded to include other regulatory functions. To understand the scope of these functions, Gogakos et al. developed hydro-tRNAseq to annotate all tRNA genes. The authors subjected a 60–100-nt fraction of total RNA to limited alkaline hydrolysis to remove structure and modifications and thus created a cDNA library with substantially increased tRNA levels. Iterative mapping provided the researchers with a comprehensive map of tRNA genes. To refine the annotation, they combined the data with photo-activatable crosslinking and immunoprecipitation (PAR-CLIP) of a protein involved in pre-tRNA processing. The authors present a human tRNA atlas that includes tRNA expression levels.