Fig. 1
From: Transfer RNA-derived small RNAs in tumor microenvironment
Biogenesis and classification of tDRs. During tRNA maturation, the 3’-trailer sequences are removed from pre-tRNA by the endonuclease Z (RNase Z/ELAC2), which results in the production of tRF-1. tiRNAs are generated by ANG cleavage of the anticodon loop of mature tRNAs under stressful conditions, including 5’-tiRNAs and 3’-tiRNAs. tRF-3 originates from the cleavage of the 3' end of the mature tRNA TѰC loop by Dicer or ANG. tRF-5 is cleaved in a Dicer-dependent manner in the D-loop or stem region of mature tRNA. Their subtypes are determined by the size and cleavage locations. i-tRFs are produced from the internal region of tRNAs, and can be classified into three types: D-tRF, A-tRF, and V-tRF, according to different cleavage regions