Welcome to the new tRNA world!

Transfer RNAs (tRNAs) are one of the classical noncoding RNAs, with lengths of approximately 70–100 bases. The secondary structure of tRNAs can be represented as a cloverleaf with four stems, and the three-dimensional structure as an “L” shape. Historically, the basic function of the tRNAs as essential components of translation was established in the 1960s, when it was found that each tRNA is charged with a target amino acid by a specific aminoacyl-tRNA synthetase, and delivers it to the ribosome during protein synthesis (Crick, 1966; Frank, 2000; Normanly and Abelson, 1989). However, recent studies suggest that the roles of tRNA in cellular regulation go beyond this paradigm. Now, tRNA is recognized as a regulator of many biological processes, and several unique tRNA genes have been discovered. Our understanding of the enzymes involved in tRNA functions has also increased and many tRNA-related diseases have been reported. In response to these exciting data, I have edited this special issue of tRNA, which revisits and summarizes the molecular biology of tRNA. The topics contributed by specialists in the field cover a wide range of tRNA research.